I have a fully built t3/t4 turbo s2k, after building the motor with a revhard kit. I learned on the dyno of bad back pressure, due to my multiple exhaust issues. I had cast iron manifold, 2.5dp, 2.5 test pipe & 2.5 hks high power (which has 2.5 pipe to split to 2 by 2.25 inch pipes to mufflers, also includes a one way air tank between mufflers) exhaust. Could only tune at 17psi with no vtec to get rid of back pressure. Temporary of course, I ordered steed speed manifold, 2.75 test pipe & straight back single 2.75 invidia exhaust. Now my problem is downpipe, i can't find any thing bigger than what i have with out customizing. Will i be okay with the new exhaust set up with same downpipe? I truely think the problem was a combination of cast iron manifold with N/A exhaust. Looking to make 450-600whp. What to do and advise would be appreciated. thx

 

is the hks high power the full catback system? that has been rumored to lose power if not make any power at all on a stock s2000.

i would ditch it for a better flowing system.

 

If you're going to be running 400whp+, I suggest you look into a 3 inch system.

 

what led you to think it was a back pressure problem? 2.5 should be good for quite a lot of power. The greddy kit only has a 60mm DP and I made 325whp with most likely a smaller turbo than you are running

 

Get a high flowing 3 inch single.

 

i think it is your manifold, i have held one of those looked it over and the runners are very small, like another poster said 2.5 dp should get you 400hp no problem, and from what i also have learned a single exhaust will make power more than a double.

 

Appreciate the comments, when i did tune the car i put 330whp at 17psi with no vtec. Still have no answer on where i can find a 3 inch dp with out having to ask the average joe down the street if can he can custom make this? Honestly i'm trying to make out with the easy way, buy one. Any links? Again appreciate it

 

I don't think its a DP issue. I think your second cam is not coming on but for other reasons. Do you have proper oil pressure?

 

Oil pressure was good during tune. I had it tuned in houston with jason herrera aka stupid fast...i trust his knowledge and he was having problems with the vtec would come on...He seemed positive it was back pressure, which is funny cause he called it seconds after seeing the car. cause i was wanting to go with the max turbo boost for kicks to see what it could do but at kept tuned for 20 or so. We will see what happens now cause i've already spent my money last week on the new parts. only part i haven't replaced from old set up was the dp.

 

That's the problem. I wouldn't trust my car with Jason. He's blown up more cars on the Dyno than I can remember.