i have a 97 gsr with a aem cold air intake and an apexi ws exhaust...i am leaning on getting the jdm itr 4-1 exhaust...i know the power gains are in the high end but i was wondering will i lose power in the lower rpm's??...will my car be slower off the start then with my stock gsr headers??any info would help

 

You will lose torque and low end. Just launch high. You've already said it though. You will have increased power in the high RPM's.

LS/GS/RS = 4-2-1

ITR/GS-R = 4-1

I think these setups would be best for these cars IMO.

 

Should have thought about this before you bought your exhaust.

The Apex'i WS is a 60MM (2.36") OD exhaust
the 4-1- has a 2.5" OD collector

It won't mate up to your stock cat, which means you are going to need to get a 2.5" ID cat.

So you are going to end up making the exhaust smaller as you move away from the engine, which is bad for exhaust flow. If anything you want to get slightly larger the further away from the engine, to prevent exhaust reversion.

 

So I I got the JDM 4-1 header, I would need to swap my my stock cat for a 2.5"?

 

yes, it won't mate up to the stock cat which has a 1.8" inlet

You also need to swap your catback for a 2.5" version, otherwise you are seriously bottlenecking your exhaust system.

 

now that ive bought the apexi ws already can you tell me what header in your opinion would be the best, so i dont bottleneck my system??

 

Don't worry about the bottleneck, get a reducer.

 

Is there a difference in pipe diameter between the WS made for the type-r and gsr?

 

even though the ITR header has a 2.5 outlet, that's just the outer diameter, the inner diameter is actually only 2.125. The apexi WS has a 2.36" outer diameter, inner diameter is 2.1875. that's still bigger than the outlet of the itr header. IMO, a 2.25 cat would do fine for the job, although a 2.5 flows a little better. just my $.02.

i hope the owner of this pic (silverb18c1) doesn't mind me posting this, but i need to use it for reference.

outer diameter measurement:


after ghetto chopped, inner diameter measurement:


as far as flow goes, you will generally need 1 sq in exhaust cross section per every 60 whp you have. so if you do the math, unless you're planning to put down more than 225 whp, the apexi WS will be fine.

-demitri

edit: pictures


[Modified by SSBP DC2, 3:41 AM 3/16/2003]

 

A reducer doesn't fix the bottleneck. The bottleneck is caused by having smaller exhaust piping than your collector.

 

Its actually 1sq in exhaust cross section per every 60 flywheel hp.

So 225 hp to the crank, or 200 -> 210whp. If you only look at the piping. The WS has a chambered muffler, so that would be one thing to keep in mind in terms of flow.

 

 

to SSBP DC2, thanks for the info man...that was tight...i think i am now sold on the header that i want...peace dude