i have a b18c1 with 253whp and 198tq w/n20 and was wondering if a header with a 2 1/2" collector would be better, i already have 2 1/2" from the header back but the collector on the header is just 2 1/4" whats the max hp you can put on 2 1/4" form header back, before switching over to 2 1/2???

also does anybody know any sites that sell colored distributer caps??

I take it that that 253whp is with the N20? I wouls not go any bigger than 2.25 unless you are planning on using more than a 75 shot and plan on using it alot.

I take it that that 253whp is with the N20? I wouls not go any bigger than 2.25 unless you are planning on using more than a 75 shot and plan on using it alot.
really??? so you think i would not have enough back pressure with a 2 1/2" collector. i dont plan on going bigger than a 75shot but i will be getting skunk2 stage1 cams in about a month. and i will be useing a 75shoe at the track. i just wnt to know what would be better for the 1/4mile. so the 2 1/4 is good up around 280whp?

Well the HP your motor is making does not determine the size of the exhaust. You have to determine the size of the exhaust by what you are doing with the motor and what the motors flow needs are. For example a 230 hp boosted motor will benefit from 3" exhaust while a 230 hp N/A motor will benefit from a 2.25 exhaust. For your setup the 2.25 will be fine but when using the N20 it could benefit from 2.5" .

Well the HP your motor is making does not determine the size of the exhaust. You have to determine the size of the exhaust by what you are doing with the motor and what the motors flow needs are. For example a 230 hp boosted motor will benefit from 3" exhaust while a 230 hp N/A motor will benefit from a 2.25 exhaust. For your setup the 2.25 will be fine but when using the N20 it could benefit from 2.5" .
well i have 2 1/2" from header back its just the collector on the header as well as about 6-8" thats only 2 1/4" should i stop wasting my time looking for a header with a 2 1/2" collector on ebay.

I don't think it will help all that much. :2cents: