C5 CU

RPM replaced my TPIS long tubes with Kooks 1 7/8 and 3inch off-road, built power across most of curve, some areas as much as 18rwhp but peak was an increase of 10rwhp. rwtq had slight increase with no loss anywhere. Have not had car re-tuned yet and expect to pick a few more hp/tq from fine tune by chris robinson. I 'll show charts with before and after header change after tuning next week....

JoeyGC5

iTrader: (24)

Cool, what size primaries did you choose?

SMOKINV8

iTrader: (6)

I've always wondered if I'm leaving some on the table with the FLP's. Your car is still 346ci, right?

383ss

iTrader: (14)

did you do !cats at the same time??? or what kind of Y did you have before?

good info!!

this should be in external engine though

TEA Brent

I've done the same swap on my dyno and lost no where and seen very similar gains from switching to kooks. Kooks are the best headers I've ever dealt with, that's why i only sell their headers.

C5 CU

The Kooks are the 1 7/8 and not the 1 3/4. RPM recommended the larger header because of my H/C and the results say they were correct (i was hesitant becuase the motor is still 346 cu/in)...no cats and the previous Y was corsa.

Chicago Crew UnderBoss

iTrader: (1)

Very nice gains eventually i will do the same thing on my 427 car that's using TPIS headers. One question, was your old set up with the TPIS through cats vs. the new set-up without cats. If yes, then this is really not a direct comparison of just the header swap b/c one would be with cats and new kook numbers would be catless. Just curiours and nice gains regardless!!!

kumar75150

I'm pretty sure he didnt have cats before either.

gomer

iTrader: (13)

He posted last week or so that the 446 before was thru cats. 446 with cats to 451 without and with bigger headers?? Also, 446 to 451 don't equal 10 rwhp
Here's a link to the thread

https://ls1tech.com/forums/generation-iii-internal-engine/123725-santa-rpm-installed-h-c-446rwhp-w-cats.html

kumar75150

my bad

he rad random cats before i think

C5 CU

The 446rwhp run was a little lean so they changed a/f and final set-up was 441rwhp (sorry for any confusion)...yes the previous was thru cats (441), but what was real interesting was the hp gain in the low and mid range of up to 18rwhp and no loss in tq (i think this part is from Kooks?)...initially i was concerned about 1 7/8 since i am 346 cu/in....with previous set-up (TPIS-RT cats and Corsa x-pipe connected to catback) i had several dynos with stock cats, RTs and gutted stock cats and open header...the RTs were only 4rwhp less than open header, the RTs were same as gutted stock cat! the RTs were 10-12rwhp gain over stock cats.....I think on my current set-up (1 7/8 Kooks no cats) that maybe 4 hp from no cats (?) and 6hp (peak 10hp) from Kooks...but i also believe we will pick-up a few more hp after tuning (?) to get final numbers...hope this clears up any confusion.