My 2004 stage 1 Inline Pro setup has a 3 inch downpipe with integral 4 inch diameter high flow catalytic converter. I'm wondering how much loss is created by that catalytic converter. Both in spool up and in HP loss. I typically run between 17 and 20 pounds boost. The car has plenty of power, but lag between shifts is terrible, often taking 2 seconds to come back on boost. And, full boost comes on at 5000-5500 RPM. There are other issues too, some of which are related to the tuning, and some may be due to system configuration. Such as plenty of boost at 3/4 throttle, but no power until throttle opens to full. (might be related to VTEC not engaging until full throttle)

So, what do you think? How much gain is there with a test pipe, over my high flow cat?

 

What turbo? Everyone with s2000s seem to be running huge turbos to make power but keep forgetting that full boost at 5500rpm is not exactly fun to drive. The cat , depending on its design may be robbing a bit of power, but very little effect on spool from my experience. Better boost solenoid tuning and turbo selection is what will affect your spool if the tune is good

 

2004 Inline Pro Stage 1, 17.5Lbs boost, GT3076r on Precision housings, Ultimate Racing 3 inch dual ex, AEM V1 EMS