Dr.K

So I got a B16 in my EF and Im running open header at the moment. My Header is a 4-1 with a 2.5 inch collector. Now I got offered a Free exhuast. But the Guy's are saying "2.5's too big, we did test's proving 2.25 is better. Im leaving the company name out but its a BIG company. So ive already got the header and Hopefully a 2.5 inch cat. If they put a 2.25 inch exhuast on is it going to bottle neck me up? I want to lie to the guy's and say im running Nitrous and a Big cam and I NEED a 2.5 inch. I really wanted to go 2.5 inch but I don't want to bite the hand that feeds me. Will this really restrict the Flow that much or Im I just Overreacting?

NOTORIOUS VR

Are you going to do any work to the motor later on?

2.5" should be ok, but it'll be loud, and you'll loose some torque... not that you'll notice it much since they make the power so high in the RPM range that you'll actually want more flow.

I say if u can get a free exhaust 2.5" is just fine and isn't much different to 2.25"

Dr.K

No...I WANTED a 2.5 inch. It give's the most power. I mean it is the difference of a hp or two.But I didn't care if it was stupid loud. I guess im jsut being greedy.2.25 should be fine. I really wanted to open it right up though. I mean its powerband is only 7000-8000RPM anyways..........lol
Sport Compact Car put a 3inch dump on a b16 and said they gained 13hp and 12lb-ft of torque over the whole powerband!!!!!! I guess backpressure is useless on today's motor's. Or high revving one's at least. But then again money talk's.Im already broke and a few hundred bucks in debt from the swap....lol

zman

iTrader: (1)

i noticed quite a big difference when i went to 2.5" over my 2.25". But i also added a 2.5" high flow cat, replaced my crappy DC 4-1 header with a good 4-2-1 header w/2.5" collector and have headwork, big cams and 11.5:1 CR.

Bullet

i would stick with the free 2 1/4" ... you're not runnin boost and even tho 2 1/2" is nice... its not necessary.

Dr.K

I ended up getting the 2.5 and I love it. I got a 2.5 cat and 2.5 resonator as well. The resonator is 18" long I think so it cut's down the noise big time. Ive heard 2 1/4's that are ear-peircingly loud after 3000. Mine is pretty quiet untill Vtec and then it scream's. Im quite satisfied and Id recomend Vibrant to anyone.

zman

iTrader: (1)

i agree i also have a vibrant j-spec 4-2-1 header w/2.5" collector to a Vibrant 2.5" high flow cat and am very impressed with it, especially for the price. The header has awesome ground clearance and is a copy of the T1R and it really helped out down low/mid range compared to the dc 4-1 i had prior. Very nice fit and finish too.

turbocivic

B series needs a 2.5, 2.25 is only good for stock

FukenRiceN

iTrader: (1)

2.5 all the way buddy if your running a 4-1 trust me and in the long run if you do more work to it,your already in the game with the 2.5