down pipe ?

chevymakesitizuzushakesit · 11-12-2008, 01:43 AM

is a turbo back system on a lly a waste of money the guy from banks said that the lly has a big enough down pipe an i would be wasting my time changing it all i need is a cat back but i think he is wrong because my d max has a 3.5 inch does it step up not sure ive been under my truck but cant tell

**n0useforaname** · 11-12-2008, 06:06 AM

I don't think it has anything to do with the size of the down pipe.....the CAT itself has A LOT of restriction. When I pulled mine off....the flow difference was amazing. And after you pull a CAT off....look inside of it...the mesh pieces that block don't let a lot of flow through....

**05 3500 2wd** · 11-12-2008, 06:34 AM

I changed mine and the stock one looks like crap for flow compared to the new Diamond Eye. It is a bit of a fight to get it out but after seeing it I would do it again. I don't know how much a difference it makes due to I changed it and the BD Exhaust manifold at the same time but with the down pipe, manifold and straight piped exhaust I am seeing a solid 300+deg EGT drop. Flow out is heat out. I think Big Red had some pictures on another post showing the difference.

**BigRedChevy** · 11-12-2008, 06:42 AM

The down pipe has nothing to do with it, the Stock downpipe is left in place anyway. Get rid of the cat with a Downpipe back system and you will love the difference.

**Kyle@XDP** · 11-12-2008, 08:42 AM

Quote:

Originally Posted by BigRedChevy

The down pipe has nothing to do with it, the Stock downpipe is left in place anyway. Get rid of the cat with a Downpipe back system and you will love the difference.

x2. while the true down pipe swap does make a difference. it's a bit of a chore to change. the down pipe back kit would make a world of difference for you.

**DSTRBD** · 11-12-2008, 09:48 AM

Agreed. The down-pipe back system will be the biggest bang for your buck. If you want maximum flow, get the Diamond Eye turbo-direct pipe.

chevymakesitizuzushakesit · 11-12-2008, 11:11 AM

i did take my cat off also y would that guy tell me to do a cat back system is he just trying to sell parts like i said befor he said if u cange ur downpipe there is no gain he said?????????????

**Kyle@XDP** · 11-12-2008, 11:33 AM

down pipe and front pipe are the 2 biggest confusions w/ the duramax. he might have been talking about the actual down pipe.

front pipe has the cat in it, down pipe comes off the turbo.

**BigRedChevy** · 11-12-2008, 04:11 PM

^^^^ what he said.

The front pipe needs to be changed, but the downpipe is not as important unless you are pushing bigger HP numbers.