what size pipe

my car has factory cat to axle pipe, and im about to change it but i dont know what sise to go to, i was thinking 2.25 or 2.5 which one whould be best . my set up right now is b18b motor S-R-I, hollowed cat,chiped ecu and fatory every thing. my 1/4 mile is 15.4 and i want to run 15.0 or high 14 for now whats to quickest way to go . i had 2.5 piping b4 but now more

[ebpda9]

2.25" i think 2.5" is waaay to big IMO

[pdiggitydogg]

2.25 is fine

i third that! 2.25 is the way to go for most NA aplications

[thermal]

unless you go turbo, 2.25 is more than enough to keep "some" back pressure.

[silver]

Originally posted by thermalfi'd16
unless you go turbo, 2.25 is more than enough to keep "some" back pressure.

not being anal but it's velocity not backpressure. too large of a diameter would cause a drop in the velocity of the gas escaping. back pressure is more of a result of the muffler(though you technically are correct but the real back pressure is caused by the muffler...eh...forget it...i'm tired)

the piping won't drop your e.t. by .5 sec. def get a header, that'll go hand in hand with your increased diameter piping. i didn't see what kind of car you have, i'm assuming it's not an integra since you're in the civic forum. i'd drop some weight. lose the spare tire, pull the back seats and seat belts. get some lighter wheels and some good tires. put all that together and a good launch and you've got a chance.

i guess it's more of what is your budget. throw a figure at us and we'll throw parts back at you and what they'll do for you.

[thermal]

you aight?

[silver]

Originally posted by thermalfi'd16
you aight?

when you work 11pm-7am, you're never ok.

[thermal]

I hear you... trust me I know. I'm in the Navy. We work almost around the clock especially out to sea...