1 7/8" vs. 2" Kooks LTH
 

At what power level would be break even point where using the 2" header over the 1 7/8" Kooks header? I currently have the 1 7/8" Kooks installed, but have to take my car back down to Vengeance Racing next month for some updates and am wondering if it would be worth it to have them swap out my 1 7/8" headers for a set of 2" headers while it is there and being tuned. I am curious if anyone has done back to back testing at the 850 hp mark to see if there is any significant, real world gains in going to the larger diameter header. I know I will give up a little boost, but that could be addressed easily enough if it was enough boost to worry about. I have always believed that boosted engines like bigger exhaust, but I would like some real world feedback if it would be worth the effort in this specific combination. I am also curious if there are any issues with rubbing/clearance issues on the 2" headers as compared to the 1 7/8.

I'm running 1 7/8 BBK coated with high flow cats. Haven't been on the dyno yet but should be at 800 to 825 on 10-11 lbs of boost on E or race fuel. Staying with lower boost this year, old motor didn't like 16 lbs.

At no point is it NOT worth going with 2” headers. Been proven time and time again you wont lose power anywhere and will only gain. I have had TSP 2” headers since my first round of mods and on extremely hard right hand turns you can occassionally hear a slight rub. That should be able to be adjusted with a slight tweak to the steering knuckle.

Yeah, I agree with this. I'm a "do it once, do it right the first time" kind of guy. While you could make gobs of power through a 1 7/8, I don't see any particular reason to not go with a 2" setup right away. However, I have Kooks 2" headers. Good fitment, no rubbing issues.

I'm good with my choice and yes the 2" will make a little more power but I should have plenty to go where I'm planning.

I like the clearance etc from the smaller header, but as stated at no point will the small header be "better" in the power making department. I had to upgrade to 2" because my goal is to make 709 WHP with the LEAST boost possible. I could not leave the 15 HP difference on the table (1 PSI).

I was over 700whp with the 1 7/8 headers @8psi. That’s a really easy target.

Boost is a measure of restriction. Just because you get a bigger exhaust or port your heads and boost drops does not mean a loss in power.

My 434ci engine made over 800h.p. with 1-7/8 headers on the dyno, started with 2" headers & lost over 20h.p. The dyno shop was very suprised & we told them 1-7/8" would make more power. My engine builder & I were just smiling after the dyno pull.

2” was proven to not lose power and gain a little torque comparing cars with the same mods at the shop. I can’t speak for others experiences...

Plus with all the random Dyno graphs I see posted showing 500hp with a few bolt on’s to the tires gets me too, no consistency in Dyno load, correction factors, etc. I wonder if people realize the changes that can be made on a Dyno to spit out a fantastic #