Will putting the 4" downpipe on the PSD help any at all if I dont yank out all the plumbing with it? My idea is to just do the DP and put a high flow muffler in. Exhaust is still in great shape, and since the restriction points (I have been told) are the DP and muffler, well if I got them out wouldn't it be enough or not? Any ideas for a good muffler? I want it to sound tough but be bearable going down the highway, as I drive lots of long miles and don't want to feel like I'm in a beater

 

Replacing the downpipe and installing a less restrictive muffler will definitely help, but replacing the stock pipe with a larger diameter would complete the job Your sig indicates that you have a chip, but you didn't mention gauges. I'd recommend a pyrometer as soon as practical.
The subject of mufflers, and how they make the truck sound is very subjective. What sounds good to one guy might not sound good to another. A lot of guys like the sound of a straight piped truck, but I don't. I've had mine straight piped, I've added a 4" low-restriction muffler, and finally went back to the stock straight-through muffler that came with it, because I couldn't stand the flutter. During low speed operation, my truck sounds stock, but when you accelerate, the sound gets throaty, and it's nice and quiet on the freeway. To me, that 's the best combination, but many will disagree. Could it be that I'm just getting old?

 

Pyro is on the list as well as trans temp and boost, just waiting for christmas to roll around They will be going in when I also put in the exhaust items. Where did you get your straight through muffler from Quad?

 

I installed a complete Stainless Steel magnaflow system and noticed only a slight change in the noise level. It's actually a 3.5" DP to 4" with a 8" Magnaflow muffler. I haven't noticed any significant changes since the addition. I regret not having put on a 4" DP. If I had to do all over, I would go with the 4" from Turbo back. I'm was running the Diablo 60 HP tune, but have since gone back to the stock until I get the Predator updated. My EGT's were running 1200+ with the 60 HP tune. I got tired of watching the EGT guage instead of the road while under WOT!

 

The 4" muffler I used was this one. It makes the sound a little more civilized, but lets the turbo whistle through. It's still a little too loud for my tastes, though.

 

yeah i was thinking pretty hard about the magnaflow system as well, or at least using their muffler or something. SO after all this my performance mods would be:

4" Downpipe, MagnaFlow Muffler

Tymar Intake

Diablo Sport Predator (most likely 60 hp tune)

Diablo Sport Accumulator Valve

Topped off with Pre Turbo Pyrometer, Trans Temp Gauge, and Boost Gauge.

That would be a pretty good start wouldn't it??? My biggest concern is being able to pull the trailer like a bat out of ****

 

You'd see a noticeable improvement in your ability to pull a trailer with that set of mods. You've already got an intercooler, so I would expect that you'd be able to pull hills without too much concern about EGT's, and the exhaust system ought to let you sound good doing it.

 

I got all hot and bothered caused by all the posting relating to "I just added my new4" complete exhaust and a 200HP chip, etc.". So, I added a Tymar air filter and QUIT. I took the $2,000 that i would have spent on all these un-necessary add ons and purchased anew set of Michelins(780) , new clutch and slave cylinder (1300) , shocks (200) , starter (300) , 100 deductible on new water pump covered by warranty. All these items occured around 72,000 miles on a 99 psd. I don't race my truck because I don't see the rationale for doing so. It is completely stock and it Pulls and runs just Fine.... , s.kuteman

 

Considering the way you use your truck, I'd say you did the right thing. That's one of the interesting things about these trucks: they're set up for the individual owner, to satisfy them. I love my truck, but you might not like it. And vice versa.

 

Mine would be completely stock if I pulled about 5-8000 lbs. at the most. Sure it does great with that. But when you got 14K behind you going up and down 10+ degree slopes, the power you can unlock from these motors with relatively little money becomes worth it IMHO. Did you like your Tymar?

 

The difference you see when upgrading the downpipe dwarfs any improvement you see from replacing the rest of the exhaust. I would recommend the downpipe to everyone, but the rest of the exhaust upgrade is not cost effective, IMHO.

Unless, of course you-unlike me-have unlimited $$$$ to spend, knock yourself out.

Gauges, however, are a smart idea. Regardless of the cost, if they keep you from cooking your engine or tranny only once, you have recovered every penny.

 

The tymar is Definitely an improvement that helps the engine breathe. I can't document any discernable increase in fuel milage but it has to help. I installed my tymar in feb of this year. Had I known of the availability of the Ford enhanced air filter I might have just opted to install it rather than the Tymar. Up until march of this year I pulled a 20' gooseneck trailer with an 11,000 pound tractor for a combined weight of 15,000 for tractor and trailer. I have a 6 speed with 3.73 axle ratio and i never had any problem with the load. I did have a 6 leaf set of overload springs installed on the rear axle as the trailer\tractor would exert about 5,500 pounds of weight on the truck. At some point in the near future when the oil refiners are finally able to standardize the Quality of Their diesel Fuel......All these trucks that have HAD Cats installed on them from the Factory are going to start BEING inspected just like the cars are currently. And, when that happens , I will NOT have to spend 600 bucks to have my old exhaust system reinstalled. It IS going TOO happen friends and it isn't that far away. ......s.kuteman

 

I keep reading that you lose some bottom end power when you put on a 4" DP.

Has anyone done a before/after dyno run with the 4" DP?

 

I have heard this too, but it makes no sense to me, hopefully someone can enlighten us. Seems to me you would GAIN low end power because of quicker turbo spool up, providing you also had an open element intake...Anyone want to help?

 

haven't been on a dyno but going from a stock exhaust on my '96 to a 4"dp and 6" straight pipe, i did notice a slight drop. it just felt a tad bit slower. it might not be that noticable with the superduties because from what i know, your stock dp is 3" round where the pre-superduties are a 1.5"x4" oval
i think it's just because of the extra flow and it's not pushing as hard i guess but after about 3 months, it just feels normal now