Alright, I got a Predator on Friday(from Motorhaven) and installed the 65hp program. Impressed as can be already, and it hasn't even fully re-learned yet. Now, I want the 100hp program but refuse to do that before exhaust and gauges.

I've searched around here for exhaust information and opinions, and it seems to be scattered everywhere and lacking some of what I am looking for. So, I would like to pose this question to the group: "Which exhaust did you go with, and what helped you make that decision?". Tell me about the sound levels(near stock with rumble, obnoxiously loud, etc.), any installation notes or difficulties, etc.

I've mainly been looking at the MBRP exhaust- just not sure about which stainless to go with. I checked out the video clips online and like the rumble it has, but not sure if the video caught the "real-world" sound of the exhaust. I also think I would want a turbo-back system, but would entertain thoughts otherwise. Also, does the MBRP downpipe have a bung installed for an EGT pyro? I know lots of people go pre-turbo(and I may do that), but I would like to know if I have an easy option otherwise.

As always, I appreciate the good information shared here. I'm anxious to get an exhaust ordered, and look forward to reading some experiences here soon!

Thanks,

John

 

I would leave the stock downpipe on and do a Cat back myself. I have the Banks 4 inch exhaust from turbo back and the sound at idle is just a little more of a turbo whistle. The rumble when you get on it is pretty cool. Interior noise is the same between stock and the Banks you can only hear the difference when you are standing on the curb eating exhaust. There are louder exhausts out there if that is what you are looking for but I don't like being obnoxious. A friend has the bully dog and it is substantially louder both at idle and especially when he stomps it to the floor. It sounds pretty good but it is really up to you what you want to do.

 

So, you recommend leaving the stock downpipe on, but have a turbo-back kit yourself? May I ask why you discourage the downpipe? I thought one advantage of a turbo-back system was EGT reduction.

Also, I should point out that I am NOT looking for an obnoxiously-loud system. I'm not trying to duplicate that glass-pack muffler sound heard on the run-of-the-mill Chevys we've all seen. I would be pleased with something with a nice low rumble at idle and a deep exhaust note at speed.

 

Save some cash, cut out the muffler and try the stock straight pipe for awhile to see if you like it.

 

I originally had the Cat back system on because Banks did not make a downpipe for the 04 when I bought my truck (exhaust was the first mod I did). Dynoed the truck with a Cat back on and then put the downpipe on about 6 months later and dynoed again. No change and the difference between the stock one and the aftermarket one is little if anything IMO. The Cat you can see through so removing it I also think is a waste of time until it gets clogged. You will get a good sound just by getting rid of the stock muffler. IF you don't want to be that obnoxious IMO get a 4 inch from the Cat back with a different muffler. Just changing the muffler will get you a better sound then stock and the 4" from the Cat back will help lower EGT's. The stock downpipe is around 3.5" and most aftermarket ones I have seen are too. The inlet pipe on the Cat is 3.5 as well so going any bigger pre Cat makes leaving it in a pain. This is just my opinion and I am sure others will jump in too. I like the Banks stuff only because I wanted performance in a box and their exhaust system is only loud on the outside when you floor it which is what I wanted but other systems are good too.

 

John,

It sounds like you and I are after a very similar goal. I am planning on a cat back as the 05 down pipe seems fine. If the new 05 systems do not require bending body metal, I would be OK with that, however, after looking at the bends of my stock DP, I can't see why this needs to be replaced.

Sound wise, we are in the same quest.

Pete (1wheel)

 

Great info, thanks!

So, the dyno showed no change with the downpipe installed- what about EGTs? Do you have a pyro installed, and if so what kind of difference did you see with the downpipe?

Thanks for being so helpful. If the downpipe is a waste, I can just get the cat-back setup and save some $$$ for gauges. So far, I have NOT been considering dumping the cat. Just don't think there would be much to gain there.

Thanks again, and I look forward to getting some more experienced responses.

 

There was little noticeable difference. My driving habits also have changed. When I first put everything in (no downpipe) I had the six gun on 4,5 and 6 most of the time. Now I rarely have it on anything but #2. I can't keep the rear wheels from spinning in any other setting.

 

I am running a stainless MBRP Turbo Back and Cat delete. Personally, I love the sound. It sounds like an F16 if you stand behind the truck at idle. If you really get on it...it will rumble, but its not obnoxious sounding...if your outside listening...it rips pretty good.

Personally, I would run the probe pre-turbo. You can go post turbo, but keep in mind every truck is a little different. Some trucks may run hotter than others...so its not real accurate unless you know what your variance is between the pre and post readings....critical if your truck runs a little hotter than others and you are really getting on it in the 100hp mode. If you go post turbo...you will probably have to shut down the acceleration a little earlier because you will need to account for EGT variance...For example, shutting down the acceleration at 850deg or 950deg post turbo (These numbers are guesses...because I cant remember what the general difference is between pre and post readings....see what I mean?). It will also affect the temp you shut your vehicle off at. General rule of thumb...below 350deg is safe to prevent the turbo from coking...again, if you really don't know what your pre-turbo temp is then......

As far as which stainless to go with....depends where you live. If you live in an area that throws salt down in the winter for example...personally, I would run the higher grade. If you live in a fairly dry area...the lower grade will suffice (thats what I am running). Lastly...the lower grade will require you to purchase the 5" chrome tip...its like 50 bucks. The higher grade comes with it.

This is JMO

 

Gibson Stainless Extreme Duals. Cat back 4" in, 2-3" out. I picked it because it looked good. I like exhaust on both sides. Two 3" equals more air than one 5".

 

I've got the MBRP XP Turbo back on my 05, and you can see the difference in the 2 pipes, side by side comparison.. the removal of the turbo clamp was probably the hardest part, other than that it was a breeze. TAKE NOTE, I have the B&W hitch, so the single system was a breeze, the cool dual is a rip and I've been talking to MH and MBRP trying to swap out due to incompatibility. Start up rumble sounds GREAT, but its barely over stock noise unless the engine is under load. I had to run catback straight pip for a couple days and LOVED it. but under load it was pretty "cackely" and you had to talk louder to the passengers. I've always been straight piping but I think I'll leave this one alone, and use the entire system since I paid the $$ for it, and not pieced together.

 

Thanks everyone...

I live in Tampa, Florida so salt and the like is not a concern. I was mainly wondering what the appearance differences were, but I suppose both stainless types look about the same.

So, what I am getting from this conversation so far is that a CAT-BACK MBRP may do just fine, and that the downpipe's effect on performance and EGTs is yet to be proved........ thoughts???

 

...yes the stainless (both grades) are very good quality and they polish up real nice. I think I have a pic of the exhaust in my gallery if you want to look.

Well...I thought I had a better pic. This is what the lower grade will look like (unpolished).

 

Ok,
my story is:
tried the muffler delete and around town it was ok... a LITTLE too loud for me, but ok.... but once on a long trip @ 80_ MPH for hours at a time... the drone in the Excursion was OBNOXIOUS ! maybe in a super duty it would be ok, but it wore on you too much in my tin can....

SO....
I went with a turbo back kit....
I'm in the DFW area and salt and all were not a concern to me either...
and since I only "SEE" the last 10 inches or so of the tailpipe. I was not concerned about stainless @ the time....

but the prices have come down drastically since I got mine.... so.... your choice...

I got a turbo back just for the sake of EGT's...
I was told that you will get about 75% of the benifit of the turbo back with a cat back....
well, I wanted all the benefit.... so I went turbo back...
AND MY 03 downpipe was a crushed STRAW, immediately felt the difference of what seemed like 25HP as soon as I drove it home...

I decided to put the cat back in for a couple of reasons:
1) after driving it for a week without it, the F-15 sound was too loud...
2) it's the law and a HEFTY fine to remove it...
3) some did dyno & 1/4 mile testing with and without cat and found no difference
4) the cat does mellow out some of the f-15 turbo whine enough to make the neighbors not throw anything at me when I pull out early in the AM
5) it's an easy match to the 4" pre-cat pipe to the cat...
the Predator is a great addition, and the exhaust will allow it to breath a bit better...

 

Nice rig, BearHunter! And thanks for the pic of the exhaust- looks fine to me(reminds me of the finish on the tailpipes of my old Saleen Mustang!)

I think I'm leaning towards CAT-BACK- to save a few $$$ and get an easier installation. I'm still reading though, so keep the experiences coming. I just haven't read about anyone seeing a power gain or EGT reduction with the downpipe, and I believe the MBRP downpipe is 3.5" just like the stock one.