1nasty86

iTrader: (63)

I currently have stainless works 1 3/4 headers on my car.. Engine is a ls2 with ported heads, 230/238, and a fast... My question is could these headers be holding back some hp? A friend I know put some arh 1 7/8 on his h/c/i ls1 and picked up nothing on the same dyno, but it was almost a year after he was dyno'd the first time. I dont want to spend the $$$ if it doesnt gain much

got-a-ls1

iTrader: (12)

i dont think it would be worth the money if you already own headers.

Sales4@Texas-Speed

iTrader: (4)

It probably wouldn't add much horsepower at this stage, but if you ever plan to put a larger motor in the car they would really shine. We have done some dyno testing and there is a small amount of horsepower to be picked up, but if you already have headers and don't plan on taking the car further it would be a pretty trivial difference in my opinion.

1nasty86

iTrader: (63)

Bumping this back up. I recently purchased a set of tfs 225 heads and plan on puyting them on when they arrive. All the higher hp ls1/ls2 cars ive seen had 1 7/8 longtubes. If 10 hp could be picked up I believe the swap would be worth it.

A.R. Shale Targa

iTrader: (2)

I'm sure they would have to be custom made but the ideal header would
probably be a 1.75" to 1.875" stepped with a nice merge collector. The smaller
tube keeps velocity off the port, the larger flows volume for higher rpms, and
the merge collector helps with average torque throughout.

01ssreda4

iTrader: (96)

I'm with TSP on this one. Gains will be there but minimal at this level.

bww3588

iTrader: (49)

Edelbrock makes or did make a 1 3/4 to 1 7/8 with a 3.5 hvmc. I have them on my car and it seemed to wake the car up at higher rpm's. Seemed to give it a little down low also.

BrntWS6

iTrader: (7)

I've been researching this quite a bit since my H/C/I swap, there's a lot of information on the GTO froums. Just like everyone else has said you might gain a couple HP.... a quality 1 3/4 headers like SW, Kooks, ARH don't really become a restriction until 500rwhp. Every back to back dyno I've read about or seen with everything being equal besides larger primaries have resulted is no gains or 1 or 2 hp. Stepped headers however I pretty much always see a 10rwhp gain all across the curve and maybe a 5rwhp peak gain. But they are $300.00 more than the 1 3/4.

02ws.sik

Maybe 5hp. If lucky