4" Exhaust options and X over pipe on the 6.5

[ShaneVanessaUK]

Hey guys.

At present I have a totally factory stock 1997 C3500 I'm trying to uprate for more power and the safe ability to pull our 32ft classic 1989 Newmar Kountry Aire 5th wheel, at present it can bearly pull its own weight and I'm getting no where fast due to the company I choose to order from but thats a seperate thread..

So started looking at exhausts and intakes and found out hardly anybody makes them and shipping quotes of $600.00 were just crazy!!! I got lucky with my last truck as I found a 4" Bully dog new in the UK for $300 fitted..

So I'm looking at getting a UK custom exhaust company "Powerflow" to build one out of 4" stainless.

Other option is go with stacks, I do like these, but then is there known GOOD companies that sell the kit minus the actual stacks whole will ship world wide.

The plan is to remove ALL mufflers and soot trap and just straight pipe it to come out in front of rear wheels.

My question is, is there a US company that do JUST the downpipe as that looks a little tricky to make due to the very slight kinks and twists, shipping would be acceptable there.

The other thing I'm looking at is the

2.5" Mandrel Bent Crossover Pipe

is this really worth doing? is there any negative effects not doing this also? its just the connections I can not get here in the UK and very much doubt the originals will work due to increase in diameter..

Any advise or info is gratefully received to this lonely UK owner

[Tannerjpowell]

Flowmaster makes a 3" down pipe and 2.5" cross over kit. I purchased the kit from summit and began fitting up the down pipe. This downpipe has a four bolt flange and is designed to mount to the factory exhaust. Just cut the flange off of the factory exhaust and weld it to whatever you custom build.

Both the down pipe and the cross over pipe fit great. I later decided to go with a diamond eye turbo back system, so the 3" down pipe ultimately was not used.

I do recommend running a pass-through type muffler. They are not restrictive (4" open hole all the way through) and they greatly reduce the noise in cab. My friend has a '94 suburban with a side exit and no muffler and I'm pretty sure his wife doesn't ride in it with him because of that... Maybe it wouldn't be so bad with stacks on a truck, though?

Best of luck!

[JorgeNY]

Im pretty sure a diamond eye down pipe can be purchased through summitracing.com

An upgraded crossover pipe will definitely help. They have mandrel bends and larger diameter pipe. The stock design is a 2 wall and often collapses on the inside from the bends causing a big restriction. The new crossover will help with turbo spool up.

[sctrailrider]

You would only need a new crossover & new down pipe IF--- you are able to do some fab/welding yourself, if you can, just get some 4" tubing local and a couple of 4" turns and fab your own. 4" tubing will fit inside the frame with some clearance, I did that and turned it as you are going to. And with a P/U there is no drone in the cab for me.

The newer (mandrel)crossover & down pipe are better than the mashed up stuff GM used, and a 2 1/4" crossover will spool the turbo quicker than a 2 1/2" will. You would be good to wrap both with header wrap to keep more heat going through the turbo and not heat soaking other things.

http://www.ebay.com/itm/FLOWMASTER-1...f61716&vxp=mtr

this one with new studs---

http://www.ebay.com/itm/6-5-Chevrole...4779d8&vxp=mtr

complete exhaust kit-----

http://www.ebay.com/itm/93-01-GMC-Ch...461eeb&vxp=mtr

[ShaneVanessaUK]

Excellent info guys, thank you.. Summit Racing.. heard of them for years now no matter what American vehicle I've owned but never used, will take a look at site now, especially if they do a kit.. its just that darn shipping cost lol!!

I was under truck today and that stock downpipe looks horrible and very restrictive..

Thanks for the Pass through tip... if I don't go stack route.. I'm thinking they will get my trailer filthy mind....

[ShaneVanessaUK]

Thanks Sctrailrider.. actually that 2nd link is the one!! e.g the Flowmaster kit, just messaged them for shipping costs as they DO ship here..

[racer55]

Might even want to consider a site sponsor here like Alligator Performance:
http://www.alligatorperformance.com/...diesel&cID=420

[JMJNet]

No, you don't want those kink and twist. LOL!!!

It should fit a nicely mandrel bent 3" Dia pipe.

[Tannerjpowell]

Originally Posted by sctrailrider

You would only need a new crossover & new down pipe IF--- you are able to do some fab/welding yourself, if you can, just get some 4" tubing local and a couple of 4" turns and fab your own. 4" tubing will fit inside the frame with some clearance, I did that and turned it as you are going to. And with a P/U there is no drone in the cab for me.

The newer (mandrel)crossover & down pipe are better than the mashed up stuff GM used, and a 2 1/4" crossover will spool the turbo quicker than a 2 1/2" will. You would be good to wrap both with header wrap to keep more heat going through the turbo and not heat soaking other things.

x2 on this. I need wrap mine. Completely slipped my mind. Looks like I'm pulling the inner fender again!