My truck is slowly coming together. Two issues I need to take care of are the intake and exhaust. Going to do the bhaf bracket i saw on this site w a 5 inch inlet tube. Anyhow that will be the easier part. Im trying to figure out what exhaust to run. I want a 4" downpipe and 5" from the downpipe back. The truck is a 2wd extended cab dually.

First off I cant find anyone who makes a 4" downpipe for the stock turbo so Im going to make one at my shop. Im wanting to order the material i need tomorow. Where can I get the vband flange for the stock turbo to 4" pipe. Or what dimesions do I need I can order a vibrant one through keystone and have it in a day. Dont really want to take the truck apart just yet. Also it seems to me that the stock downpipe has way to sharp of bends in it. Has anyone ran into issues with straightening it out a bit. Im only seeing the heater box as a source of potential trouble. Im just going to cut and weld mandrel bends till its to my liking. Probably heat wrap it also.

Second. Is there a 5" system thats close for our trucks. The silver and red gen 1 dodge in diesel power looked like it has a manufactured tailpipe on it? Thinking it will save me alot of trouble if I can mod a manufactured system rather than completly build a tailpipe. Forgot to mention I want stockish location for the tailpipe exit. Downpipe to tail pipe is rather straight so that will be easy part. Also if i can buy a system and mod it it may save me a few dollars in material as well as not tie up a lift for a day.

thanks for any help i can get. When Im finished with the exhaust ill post pics promise.

 

well; expandit makes a 4" kit that is a 3" DP then 4" back, bullydog makes a full 4" with the 3" flange. and honestly 4" is plenty. you'll get more benefits from upgrading your turbo and using the HX40 style DP for a true 4" turbo back. you just have to dent the pinch welds on the firewall and the bends are straightened out a bit. but as it sits, the turbos outlet is going to be the most restrictive part of your exhaust system. to a certain point an aftermarket exhaust will help but it wont take much before its just over kill. i have a 3"-4" kit from bully dog on mine and the turbo is quite responsive, even over my practical 3" straight pipe that dumped out infront of the wheel. so... if you can make a 5" work then go for it. just stating the facts bud.

 

went with a complete kit from source. It was made for a 4x4 but i got it to fit nicely on my 4x2 dually. Had to cut about 6 inches out of the first pipe after the downpipe and 4 to 6 out of the tail pipe where it goes to the muffler. My truck is a extended cab. Also remade all my hangers as mine were non existant. SIde view you cant see any of it from the drivers side and the passengers side you can just barely see the muffler. They are working on a kit for the 4x2 now though.
Dont have any real driving impressions yet as I ran it for a week with just a dp. Then swapped the fuel pin. It seems to run better now though than w the fuel pin installed and a dp only. I definetly need to pull my pin out and check to see if its travelling all the way. Just seemed worse than the stock pin turned ninety degrees. At least I can now put the 366 spring in and tweek the pump some more. So much to learn still.

 

i can't believe that an aftermarket pin didn't do as much as a stock pin, all of them fuel much harder then a stock pin, check to see if you have the groove lined up right

 

I got a full 4" DP from Rip Rook's Fair Shake out on the west coast. a little over 200 delivered. Fits like a glove and mates directly to the S1 on my 92 I/C motor. So you can find them, but it takes a bit of hunting. He even has a full 4" that mates to the turbo. I run straight pipe, so I just got the DP and run out before the wheels.

Droop

 

thar has been some talk that the Bulley dog kits is not a full 4" system ?? both Source Auto and Stans headers are a full 4" ststems ken

 

Most of the "name brand" systems I have run into are 3" DP to a 4" system after the DP.

When I was buying parts, it was almost easier to goto the 5" pipe after the DP because that is the size on most of todays medium and heavy duty trucks. However, I would have to cut the DP back a few inches to clear the 4 - 5 adapter and flex pipe around the trans mount, so I just looked around until I found 4".

Check your state laws, but in a lot of states, flex pipe is legal for diesels and is standard on a lot of heavy trucks' systems. It is also cheaper to buy two or three feet of stainless flex pipe to go around the transmission mounts and transfer case than to get elbows and what-not. The one 12x12 - 45 I bought was just as expensive as three feet of flex line!!

Also, the cool thing about Rip Rook's DP is that you can buy the 4" flange to replace the 3" flange at the turbo end when upgrading the turbo to a real turbo from stock and save the DP. You just cut the welds for the 3" flange and weld in the 4".

In all, I still spent close to $400 in parts, which is pretty close to the full price of a complete system with muffler at $5-600. I have to look at it as though I have an easy upgrade path to running a stack later on as I would just cut a bit of pipe back and install a 90 to go up the back of the cab.

Droop

 

from bully dog website.....

Bully Dog Technologies’ Rapid Flow Exhaust Systems are designed and built with absolute minimal degree angles on bends. This will create the most free flowing low back pressure system in the industry allowing the turbo to move air more freely, reducing exhaust temperatures. Dyno results have shown a 10-20hp gain in horsepower by simply switching from stock to a Rapid Flow Exhaust System. This will also lower exhaust temperatures by as much as 200 degrees depending on size upgrade and horsepower output

This system has a 3" down pipe.

Bully Dog recommends using a 4” exhaust system for horsepower applications less than 450 hp, while the 5” systems are recommended between 450 to 550 horsepower applications, and our new 6” systems are recommended for trucks producing more than 550 hp


where do i find a 4in down pipe?

Stan's
source
Rollin smoke diesel

any were else?

 

If you look in the sticky I bought a expandit kit and used a 4" DP from a 2nd Gen truck. With a stock Turbo a 4" DP is not needed. And when you upgrade the turbo you can step up to a 4" DP.

 

puredieselpower.com has 4" dp