J_Siafu

F.A.S.T 92mm
Obx longtube headers (everything behind the fake cats is stock with muffler delete)
Ms3 cam springs and pushrods
Stock cai
Stock ls6 heads

Just curious finally have the money to make it fast you're opinions are welcomed

bigti99a

iTrader: (16)

400ish rwhp

J_Siafu

Im really shooting for like 430whpish is it the heads that holding me back

itsslow98

iTrader: (18)

You should be right around there with the FAST and MS3.

heavymetals

iTrader: (3)

My $0.02, I would think around 390rwhp.
Get a bigger throttle body and a tune.

itsslow98

iTrader: (18)

I made 400 with a smaller cam, and high flow cats on a stock ls6 intake manifold/throttle body. If he doesnt make over 420rwhp with thos emods something is wrong.

J_Siafu

Thats the vibe i have been getting ive heard the stock ls6 heads are pretty good would you upgrade the injectors if this where your car?

itsslow98

iTrader: (18)

Yea, you are going to max out the stock 28s. I would go with 36lbers.

J_Siafu

Yea i was thinking that as well i might throw electric cutouts in as well just for some extra kick when,im feeling rowdy

Naf

iTrader: (1)

are the headers 1 3/4 or 1 7/8?

1 7/8 will lose power but the 1 3/4 will benefit a stock 5.7ltr block...

itsslow98

iTrader: (18)

Absolutely no idea where you get that info from.

J_Siafu

Yea i was about to ask that

rand49er

There MIGHT be some very slight difference mid-range, but I'd doubt that there'd be any noticeable difference at peak.

Naf

iTrader: (1)

If you run 1 7/8 headers with a 3" collector on a 5.7ltr engine you will be sacrificing a lot more power for peak. On an engine of that size it would be recommended to run 1 3/4 with 3" collectors for then you gain across the power band.

Running bigger tubes needs more air to pass through or else it will work against you making it harder to tune the car and get it to run properly.

Its like running 3" exhaust with cam and headers. You wont benefit from the extra cfm for you havent pushed past the limits of the 2.5" catback.

I say this confidently with experience. I have altered everything in my car and finally got the formula right. I am running 1 7/8 with 3" collectors and 2.5" catback, power is plentiful and there is no end to the push...Idle is smooth (which i have witnessed first hand recently) am waiting for my body shop to pull out the rear fenders another in so i may run it on the road and see how she performs...

My tahoe went through the same treatment. Had 1 3/4 headers for my 5.3 and modified 6.0. Made 425/420 with 1 3/4 headers and single 3.5" catback. I then tried 1 7/8 headers on the setup and lost 25/20 making it only 400/400 at the wheel after tuning. I then upgraded to a 6.6 and used the 1 7/8 headers. Made 500/500. If i use the 1 3/4 headers i will gain torque and lose Hp...

So size matters and if you get the combo correct you will have all the proper power in the world...

NIKDSC5

iTrader: (10)

If you break 420 I will be impressed. Max effort LS6 (with heads) 450 RWHP. Heads are usually good for approx 40 WHP. So.........yeah.

itsslow98

iTrader: (18)

There isnt a single reputable tuner who will believe you lost 25/20 by ONLY swapping the 1 7/8 for 1 3/4.

Its just not true.

rand49er

tru dat

jclayc

iTrader: (8)

I have an 05 LS6 with an aggressive cam, trick flow 220s, a forged bottom end, a FAST 92, LS2 TB & Kooks 1 3/4 headers (among other things) . Took it to Slowhawk Performance & made 405hp/366tq. I expect I have a little loss from the forged bottom end so maybe you'll hit 400.

ryridesmotox

What's your static compression? That plays a big part in the power equation.

punishmentcycle

iTrader: (6)

If it were me id keep the ls6 intake and spend the grand on porting the heads. The fast intakes are nice but not really worth the money unless ur max effort or FI. Heads will give u more power everywhere with room to grow.