I decided to swap to 1 7/8" headers after talking to people telling me my 1 3/4" could be a choking point in my setup. Wasn't expecting much....maybe 5 rwhp, but I wasn't out much money doing the install myself after selling my old Kooks headers so WTF.

ONLY thing that changed on my car was swapping from Kooks 1 3/4" to Kooks 1 7/8".....same dyno....after a touch up tune.


Setup:

2.5 LS6 heads from PRC
Torquer V3
FAST 92/92 ported
98mm Lid
UD pulley
Kooks TD's



Old numbers WCF
441.6 hp
391.4 tq

New numbers WCF
461.4 hp
406.5 tq

Again, ONLY thing changed is from Kooks to Kooks headers larger primaries.

 

Thats alot more than I would have guessed. Very nice

 

Wow, that is pretty damn impressive

 

yeah wow....

 

Those are definitely some solid gains!

 

Ive thought about switching to kooks ss and a borla catback. If i knew i could gain power and get phenominal sound i would do it in a heartbeat.
Your results have helped aid my decision. Thanks.

 

Wow 20hp 15tq very nice gains

 

I agree. That is double of what I would have guessed.

 

^ You and me both, I was shocked when the numbers popped up. Hopefully I can help people with their headers decisions with this, the primary debate still comes up here.

 

Very nice. I think the fact you are a heads and cam car is what really made the switch worth while. A bolt on car would be a lot less

 

Holy hell. LOL. And you didn't lose anything even down to 2500 RPM.

TSP did a test a few years back and had smaller gains (but gains everywhere) with their 1-7/8" vs Pacesetter 1-3/4" on a stock LS1 with just a FAST intake. Everyone wanted to see the difference between like Kooks 1-3/4" and 1-7/8". Hot damn! The True Duals are certainly helping

 

I can believe it. I went from mac 1 3/4 to Kooks 1 7/8's....think how big that change was....lol Good gains, these things like to breath!

 

Great gains congrats on great mod..

I honestly would never buy 1.3/4 headers unless I want to keep the car as Boltons only...

 

Nice gains.

Are the new 1 7/8" headers the new design with the Merge collector? I have heard that alone can make 10 + horsepower with out even changing the tube diameter.

I hope I see similar in my change from a 1 7/8" to a 2" with a merge collector.

 

with stock heads and cam I gained 5+ hp switching from pacesetter headers w/ open cutout to kooks 1 7/8 headers and true duals. I have a tight gap on my plugs aswell and the redyno was in warmer temperatures by about 15 degrees.

amazing gains, those headers really wake up with heads and cam.

 

they were also very easy to install compared to the pacesetters and great fit n finish

 

Definitely great gains!

 

Thanks for posting this info! I was hesitant about purchasing KOOKS 1 7/8" headers because I thought the 1 3/4" size would be more ideal for down low torque. (My goal is to hit 350TQ at 3000RPMS). This info makes me feel good about purchasing the 1 7/8" size headers!

I see you went to Straightline - live in the Chicago-area too?

 

I wonder what the TSP 1 7/8ths setup would do over the hooker 1 3/4s in my sig?

 

As JakeFusion mentioned, it's interesting to see there was no loss at all in the powerband even at ~2,800 rpm's. Excellent gains across the board...