I bought a Flo-Pro 4" system a few years ago and was never real happy with the fitment on the downpipe...real bad actually. Had to bang dents in it and the OD on the bottom end doesn't match the OD on the midpipe making the coupler not fit them together right. Any idea if an MBRP unit that Riff-Raff sells would swap in so I could get rid of it? Not sure if these different systems tend to line up the same way or if it would just be totally off. One of those things I'd had in the back of my mind to fix at some point. I replaced the coupler awhile back and realized then it was the downpipe itself that was the problem.

 

I would bet yes, but best to ask @Riffraff Diesel they will not lead you on.

 

I emailed them and asked and they basically said the same thing..."probably but not sure." I would guess they all line up close enough as well but I guess I'll find out. They have the 409 stainless MBRP one for about $150. I can remove the old one first and compare it closely before attempting to install it.

 

Well, went out there to have a closer look at the shape of the downpipe to compare it with the MBRP and Diamond Eye replacements and it looks like the MBRP is closer so I ordered one of those.

I also found that the one in there had rubbed a hole in itself where it was resting on the up-pipe, so that explains the extra droning/humming noise I've been picking up that I thought was the alternator bearings last month. That was partially my fault though for banging dents in the downpipe that left an edge to rub. I haven't taken it out yet...might as well leave the truck drivable until the new ones shows up but I sure hope the up-pipe isn't ruined also. I don't know what kind of luck other people have had with aftermarket 4" exhausts but this one I bought was pretty darn crappy. It was actually the midpipe side that had too large of an OD for the coupler and the downpipe side is too small to where I couldn't tighten the coupler down enough to keep it snug, which was part of the reason it was resting on the up-pipe in the first place. Just frustrating. I almost wish somebody made a stock sized 3" replacement. Not as many replacement options for the cab and chassis trucks either compared to the pickup trucks. Some sort of custom ground pounder setup coming off the downpipe has occurred to me as an idea.

 

some of the OBS cabs were not made to same spec and people had to cut and bend pinch welds for some more room and a fw had to cut some holes in the floor.
crew cabs were not as bad to do IIRC
sagging cab mounts dont help with clearance either

 

I have 3.5" mandrel bent, full diameter stainless steel down pipe on my cab chassis that fits without issue and maintains all clearances, at all temperatures (the exhaust system g r o w s when heated, which is why the exhaust hangars swing fore and aft.)

The downpipe is made by Banks.

The Banks 3.5" downpipe even clears the right hand frame rail heat shields that I added from the Excursion. (Designed to shield the Excursion's rear a/c lines that my cab chassis doesn't have, but the same shields protect the elastomerics in the upper eyelet of the OEM crossaxis ball joints in the end links for the anti-sway bar.)

I've had it on the truck for 22 years without any issues.

 

Yeah I really wish I could have gone with a full system from Banks or MBRP but they didn't seem to offer anything for the cab and chassis models. I have no doubt the fitment is better on those bigger names. Not entirely sure what would happen or be the problem if somebody tried installing a pickup truck exhaust on a cab and chassis (anybody?). Maybe the clearance around the rear mounted fuel tank?

I'll see what happens when the MBRP downpipe shows up. Are there shims that exist to make the downpipe end fit better into the slip coupler? Part of the problem here was that the midpipe piece has too large of an OD, so it stretches out the slip coupler to the point where it won't clamp down properly on the smaller downpipe end. That was type of coupler the exhaust came with but now I am wondering if that was some sort of screw up. Take a look at 9:08 on this dude's video and it looks like he's got some shims underneath that slip coupler. That's kinda what I need.

 

I have no clue what MBRP offers, but I can speak about Banks with reasonable familiarity. I've stood in the Banks buildings watching the mandrel bending machines forming the downpipes and exhaust systems.

With confidence, I can tell you that Banks makes an exhaust system for chassis cabs. I've had a full Banks Power Pack exhaust system (CARB Approved by Executive Order) for the last 22 years.

The downpipe makes no difference between pickups and chassis cabs. Where the downpipe will differ is whether or not you have a Banks Power Elbow, a Banks Brake, or simply the stock EBPV valve. I kept the stock EBPV in place, even though I have a Banks Turbine housing (1.0 A/R... also CARB Approved).

The difference between pickup and chassis cab offerings is from downpipe back. (There are some differences between trucks that came with a Diesel Oxidation Catalyst, but my 2000 automatic didn't, and I don't suspect yours has a DOC either).

A 4" diameter exhaust system is available for the pickups, whereas the chassis cab offerings from Banks are limited to 3.5". The reason for this is exactly as you suspect... the aft axle fuel tank.

It isn't just the fuel tank... it is actually a combination of four things:

1. Frame rail vertical web distance apart (34" narrow frame chassis cab vs 37+" wide frame pickup)
2. Frame rail horizontal flange width... (2.74" wide horizontal frame flange width in chassis cab vs 2.36" wide horizontal frame flange width in pickup)
3. Frame rail kick up over rear axle, or lack thereof (no kick up in chassis cab, slight kickup in pickup)
4. Presence of rear axle fuel tank, or lack thereof (aft axle fuel tank present in chassis cab, not present in pickup)

Items #1, #2, and #4 make the biggest difference, and the clearance between #2 and #4 is the main reason why Banks didn't offer a 4" for the chassis cabs.

Still, the Banks 3.5" downpipe flows more volume per unit of time than the necked down stock 3" down pipe.

Unlike whatever downpipe the dude in the video posted was installing, the Banks downpipe does not require the removal of any oem exhaust heat shields.

Also, unlike that Facebook marketplace derived downpipe in the video, the Banks downpipe includes a downpipe mounted heatshield similar to the heatshield that is directly mounted on the OEM downpipe.

I'm not posting to push Banks... I'm just posting to refute to the assertion that Banks didn't have anything available in the way of down pipes or exhaust systems for the chassis cab. I can say that isn't true, because I've been running a full Banks exhaust system on my chassis cab for decades now.

I have no idea what MBRP offers though.

 

MBRP is an Ontario Canadian outfit and they make some pretty trick stuff...a full 304 stainless exhaust for the pickups. I bought one for Mom's early 99 several years ago and it's pretty nice. Don't think anybody else makes a full 304 stainless turbo-back system like that

If I had known Banks offered a full kit for the cab and chassis trucks, mine being a 350 but assume the 450/550 version would be no different, I might have gone that way. Not the cheapest stuff they offer but I know they put the R&D time in to make sure it all lines up right. Judging by the frustration I now find myself in with this, paying the extra money for something that fit better from the get-go probably would have been a wise idea. Try as I might though, I couldn't find any listing for a cab and chassis exhaust system in their online catalog. At some point if I can't find a happy fix for the current setup I might have to see if they still offer it.

I appreciate the details there in the cab and chassis differences. I can attest with 4" tubing there was some issues with it moving back and forth and making contact with the front corner of the fuel tank. I noticed it pretty quickly and was able to use a big zip tie to keep it from moving side to side as much and rubbing on the tank. A little ghetto and one of the other things I was less than satisfied with. I have a 1.15 A/R van turbine housing with the Riff Raff van turbo/super duty downpipe adapter (which for some reason I don't seem to find listed any longer in Riff-raff's online catalog), but I doubt that's making any difference. No, mine didn't ever have a DOC either I don't think.

I went to my local auto parts place today and was looking at all the different types of clamps and couplers they had on the shelf to see about a do-it-myself solution. I will take some measurements of the downpipe and mid-pipe OD's where they meet when I take the old one out. It might just be that system has poor enough fitment at that connection point to be a real problem that needs a DIY hackjob solution to fix it, or just replace the whole system. As I said, frustrating stuff.

Any reason this Banks kit wouldn't work on a cab and chassis? This kind stabs right at the heart of my troubles with the downpipe and front midpipe setup. Obviously I would have to cut the existing pipe at some point further down and splice it in, or maybe if it goes far enough aft of the transmission x-member just do a 4" turn-down tip and delete the over axle rear part.

https://bankspower.com/products/turb...l-power-stroke

 

4" tailpipe section for an excursion should fit as well with the rear tank.

 

On what basis?

 

I can't help you with Banks's website.

I've stood face to face with Banks (he is tall too) in his office and argued that the practices of his phone sales team (back then) could use some revision, and he countered that he argued with his marketing team about the use or non use of the color blue on his website.

He used to always buy red vehicles, because magazines (before the internet) would generally put red vehicle on the cover, and he wanted to make sure any photos related to any articles about his products made it on the front cover.

So I can't understand why his website currently is interrupted with some sort of sick spin the dial fuel card give away pop up, when all a person wants to do when visiting the Banks website is learn about Banks products.

Seriously, I don't know how a person can find anything on Banks website as it is at the present moment. Even the vehicle application feature has been stripped away. The Banks website has been better before, and it will no doubt be better again. It is always changing.

He is ALWAYS on the move. Always switching it up. Always adapting. Always trying something new. He doesn't stand still, nor does he rest on his previous laurels. He moves his business with the same speed and attention to detail as does when he conquers records on the salt flats. But he has always seemed to me to be somewhat disconnected with how his sales and marketing teams manage his store front., even while he excels in how he manages his media presence.

Anyway, I deal in part numbers, not spin the dial pop ups. Fortunately, I still have stuff on paper. The Banks website is impossible to navigate right now. It is horrible.


52152 = Upper Turbine Outlet Pipe (the downpipe, with a bung welded on for a post turbo EGT probe)

Do you have an early 99 or a late 99?

If Early 99, then
52162 = Lower Turbine Outlet Pipe (what you call the "middle pipe")

If Late 99 or later, then
52164 = Lower Turbine Outlet Pipe (maybe what you call the "mid-pipe"?)

No DOC CAT, so reuse the stock 3.5" straight pipe after the lower turbine outlet pipe and ahead of the muffler.

If you want to replace your stock muffler with something that was engineered on a flow bench (the same flow bench that I tested enclosed air box systems with), then consider the Banks Dynaflow Muffler, which has a toroidal ring at the entrance that appears counterintuitive when looking at it, because it necks down the entrance of exhaust gasses into the can.

But that smooth radius necking down is actually intentional. It works like the toroidal entrance of a black hole. A venturi effect is created because of the constriction at the entrance, and the exhaust gasses actually accelerate through the venturi and expand into the wider and less restrictive chamber of the can. The net flow effects were tested by setting these mufflers up on the flow bench, with various sized venturi rings fixed to the entrance, and gathering data.

If interested, then the Banks Dynaflow Muffler part number with the 3.5" entrance that will mate with the stock straight pipe that spans the gap between the lower downpipe and the muffler is...

52432 = Dynaflow Muffler Assembly... which comes with exhaust hangars already welded on just like a stock muffler, but unlike a stock muffler that is a staggered flow, the Dynaflow is straight through, like a Walker Big Truck muffler. The hangars are positioned such that they work with the stock frame hangers and swinging donut elastomerics.

Finally, the piece that fits between the frame rail and the aft axle fuel tank. Keep in mind, the width of the lower frame rail flange at the point where this tail pipe wants to sneak past the forward curbside corner of the aft axle fuel tank is actually 4.2" wide, because that is the area of the lower fame flange that intersects with the frame cross member just ahead of the fuel tank.

Where a frame cross member intersects with the frame rail, the frame rail flanges flair out to meet and support the crossmember so as not to have a sudden transition. Heavier chassis frames like the F-650/750 and F-59/53 have a different frame cross member attachment methodology, where the crossmember is affixed to the frame web, and the rail flange remains constant.

But the F-350/450/550 chassis cabs are different in this respect, because the crossmembers are attached to the flanges, so the flanges flare out another 1.2" wider than their nominal 3" width in order to meet the crossmembers.

This is why an Excursion tail pipe will not work with a chassis cab frame. The Excursion fuel tank is an entirely different shape, and material. The Excursion frame rails are 37.6" apart, as opposed to only 34" apart. And the Excrusion frame rail flanges are 2.x" wide, whereas the chassis cab frame flange is 4.2" wide right where the tail pipe coming out of the muffler wants to dive down behind the rear axle and between the fuel tank and the frame.

So, the chassis cab tailpipe pieces are:

53448 = Monster Tailpipe

53449 = Monster Tailpipe Extension (to bring it out from under the chassis, side exit).

I don't have a part number for the polished tip. That was another argument I had with Banks, but I think I won that one, although the result came to market years after I made the argument.

My argument was that people wanted to see three things in an exhaust tip:

1. A radiused rolled edge (at that time, Banks tips were single wall blunt cut sleeved over the base tailpipe, forming a double wall, but with both tubing edges showing)

2. An angled cut (at that time, Banks tips were flush cut up and down)

3. An ovalized exit (at that time, Banks tips were simply round circular exit)


Eventually, Banks did change his tips to include all three of the suggested design elements, and more ideas that I didn't suggest, like his logo, the color black, cooling vents, etc.

I don't have any part numbers for his latest tip designs, but the tips he has been selling for the last 15 years look a heck of lot better than the tips he was selling 25 years ago.

Hopefully, you can make all the stuff you already ordered work out to your liking, but at least you have some part numbers as a baseline, should you decide to go with Banks products.

BTW, I used the "F-450/550" printed book for the parts. Banks probably doesn't list an "F-350 chassis cab", but the frame dimensions that are relevant to what you are trying to do are the same between the F-350/450/550 chassis cabs.

 

Fab post Y2K! Many details that need to be graven in stone, now are.

 

Okay so it looks like there is no Banks part number for a "cab and chassis exhaust" (a complete one) from what I am gathering here. (Mine is a late 99.) You'd think there would be plenty of those to sell especially as those trucks get older and the original exhaust systems start to rot away and need replaced. Maybe it's a California issue with those larger trucks now since I know he's a CA company.

This part # 53581 that I linked in the last post...it's listed for a 1999.5-2003 F250/350 so I'm assuming that means it's 4". What I'm really trying to hone in on is whether that "front mid-pipe" (the very first piece aft of the downpipe with the first hanger mounting point) in that kit would line up with the hanger mounting point on my F350 cab and chassis. If so, I think I might have to give the that Banks kit a consideration as more of a permanent fix than just attempting to swap an MBRP or Diamond Eye downpipe into the existed setup, which I am guessing still might not fix the sloppy connection problem with the existing front mid-pipe.

I was under the impression the frame on the pickup trucks and chassis cabs were essentially the same until the frame aft of the cab narrows down to 34", which would lead me to assume the first hanger mounting point on my truck is the same as a pickup, but not sure. There is also the question of whether it would line up on a "port/starboard" orientation with the "rear mid pipe" on the existing exhaust but obviously there's no way to know that unless I just bought it and tried it. Worst case if it didn't I could delete the existing exhaust aft of that 2-piece Banks kit and do a 45* turndown off of the Banks front mid-pipe and do a makeshift weed-burner setup. That could work as long as the hanger mounting point lined up...just a downpipe with a turndown tip on the end would be a bad idea as a long term fix since it doesn't go back far enough and there is no support at the bottom end. It would just be dangling by the v-band clamp that connects it to the turbo. You'd need that first hanger on the bottom the front mid-pipe hangs onto.

I called and canceled the stainless MBRP ($182 with tax and shipping...). What I think I might do first is just try the cheapest aluminized replacement downpipe from Diamond Eye. $115+tax with free shipping off Ebay and see what happens. If that's not to my liking either at least I won't be out that much on it but who knows it may fit better. Then the Banks solution would be the next logical step. At the price they want I think I'll try the cheap option first.

Great info as always.

 

The Diamond Eye replacement downpipe does fit better...wrestled it up in there yesterday and was able to re-use the rest of the exhaust, happily. These 4" downpipes seem to all be pretty similar in design and routing, so it swapped into an existing system from another brand no problem. However that one I pulled out from the original Flo-Pro system definitely was junk as far as fitment. Could tell so by laying them side by side and looking at the top neck part that clamps to the turbo. Diamond Eye had a nicer bend to it that allowed it to snake it's way down the firewall without hitting anything, and comparing the other ends the bad one was way off on the OD measurement when I used a digital caliper to compare them. The OD/ID lap joint is much tighter and more precise with the Diamond Eye. Luckily...and I do mean that...the up-pipe was okay with just a couple rub marks on it . Sure as hell didn't want to have to go pulling those out again to fix or replace them. Those are the expensive International ones too. Maybe the steel is harder on those stainless pipes vs the cheap aluminized mild steel the downpipe was made out of? I'm not much of a fan of these aftermarket exhaust systems anymore and would gladly go back to the stock system if I could snap my fingers and make it happen just to avoid the fitment headaches.