I got mixed intel if you wanna call it on which I should go with im stuck still right now with the 1 3/4 ,as I thought for the 1 7/8 are for big hp engines that have forced induction or a stroker. My setup if gonna be my stock ls6 heads with a ms4 cam with 150 shot and other small things...so is going with 1 3/4 right?

 

about .125 inches.....

 

about the same difference as a fast 90 to a fast 92

same price for a set of kooks from us it looks like.....^ditto

 

We've actually tested this on the engine dyno with a completely stock long-block and then with an aggressive heads/cam combo. Even on the stock long-block you pick up enough power to make it worth your time and money (break even until about 2000rpm and you're up from there on). On the more aggressive combos (H/C, strokers, power adders) you stand to benefit even more!

 

I can't remember if it was Hot Rod or Chevy High Performance that did this test a while back but they got similar results, even a stock LS1 breathes better with 1 7/8. The SBCs they had tested in the past didn't pick up anything with larger primaries, but the LS1 seems to be different.

 

I think for ls1's over about 380-400whp, definately get american racing 1-7/8's, make it the last set you'll ever have to buy.

 

thats what I hear I should go with ...tks