Hey everyone. First off I would like to say that I HAVE read a lot on the FI forum. That being said, I have a 99 base model with STOCK INTERNALS, and a turbonetics t3/t4 turbo on it. I bought it as a kit. It came with a cast exhaust manifold, which i heard was better than chrome pipes due to flow. I have a fairly big intercooler, and charge pipes, 880cc injectors, bigger fuel pump, MSD 6 digital ignition with boost retarded, the ECU was converted to OBD2, what ever one is programmable be it obd1 or obd2, And i have 3" exhaust from down pipe back. Now with all of that said, I have a few questions to ask all of you smart people... The exhaust side of my turbo, where you look at the turbine, I measured it and the diameter is 2 1/8". I have talked to a couple of people about a down pipe size. Some say 3" and some say your DP doesn't have to be bigger than the exit on the turbo. Well I have a 2 1/4" DP that runs down under the motor and just past the oil pan where it goes to the 3" exhaust. My question is that if this is restricting flow? And i heard someone say that DP size has alot to do with where your torque is on your RPM band. Im a little comfused. Should i scrap my 2.25" DP and go to 2.5 or 2.75?

 

the cast exhaust manifold KILLS power on h22's. way more than your downpipe is. i'd run atleast a 2.5 dp and a 3 inch if possible....but before you spend money redoing a downpipe, get a good exhaust manifold on there.

 

Are you going to ask me what manifold im running? And what manifold do you think is best? I was told to buy this manifold over a tubular manifold for increased flow

 

a cast being better than a tubular hmmm ok what manifold are you running and a pic plzzzzzzzzzz

 

no, there is no need to ask you which manifold you are running because you already stated it is cast. i have built and tuned a TON of h22 cars, and each and every single one of them that have had a cast and/or log manifold on them have been down on power substantially compared to another similar set up with a tubular manifold.

 

So what kind of mani do you suggest is better?

 

Lovefab, synapse, custom tubular.

 

Something like this?


http://www.synapseturbo.com/mm5/merc...kits_manifolds


Kind of pricey, I see some tubular ones on ebay, I know...

 

I'de get the Spoolin Performance manifold for the H-series. SPfab Quick4 -- $ 495.00
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http://www.spoolinperformance.com/sp...ick4-p-59.html

http://www.spoolinperformance.com/images/minime1.jpg
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Is such big piping needed on 10 psi? Will it really boost flow that much? It looks BIG!!! And my cast has the turbo on top, how will this mani change my setup?