BIG HP numbers are sexy has all heck, but if your not always driving above 6400 rpms, why have them? Bench, Bar and forum racing?

I run a small cam 224/224 581/581 112+4 with a stock LS6 intake and tpis 78mm tb. intake was polished a bit to clean up some ruff edges but not really ported.
243 heads, again polished a bit to clean up any ruff edges but not ported and 918 springs. My own CAI like the Honker.

LTs, high flow cats and straight pipes. Underdrive pulley, high volume oil pump and an oil accu-sump with oil cooler.

405 rwhp and 407 rwtq. Last winters dyno.

at 2500 rpms right at 390 rwtq.

now I dont drag race but do track days on road courses. I can just about out accelerate almost anything out of a corner and UP to 125 mph. Over 125 mph I am toasted. But they have to catch me first,

what I was getting at, get a smaller cam and set up that will give you immediate throttle response, and off the line torque. It may not be a dyno queen, but you will love the ride.

If would have done it over I would have put in a 224/228 581/588 112+4 cam or maybe a 224/230 588/600 113+4

 

I am jealous. This is a ton of 2,500 RPM RWQ for a 5.7 liter! Your tires must spin when you exhale.

 

As a read this post and re-read the original, I began to wonder whether your engine is "choked for air." You have good heads, headers and the LS6 manifold is pretty good. Your power output seems good. Why do you think that your engine is choked? If you want more top end or mid-range, a new intake manifold will help and you don't need to turn 6,400 RPM's to get big gains. The FAST 90 starts outdoing the stocker in the mid-3,000's. There are other good manifolds, too.

However, you mentioned in the quote above that the Cheatr cam is soft until 4,000. You also mentioned in the OP that you didn't want to lose low-end performance. Do you really mean that you would like to improve your low-end performance? If this is the case, I would steer you away from the manifold as a first stop.

I also wonder about your comment on the Cheatr cam's softness below 4,000. The Cheatr is usually recommended for folks who want more power across the power band and a decent idle. It is often used in automatics. The Cheatr should be a good low-end cam. Is your cam installed straight-up, retarded or advanced? Switching it from straight up to 4-5 degrees of advance would make a relatively large positive difference to your low-end with a relatively smaller decrease up top. I don't know how hard it is to change this parameter with the cam already installed but it might not be that hard. Your tuner would know.

Is your low-end tune optimized? Do you have 1 7/8 headers? Either of these could be serious problems.

How much RWTQ do you have at 2,500 RPM's? Maybe your torque standards are very high.

Is there something else wrong? Your car should not be soft up to 4,000 RPM's.

If everything checks out you might want to look into advancing the cam. This could be 8-10 ft pounds down low. You may also want to use a thinner head gasket to pick up 8-10 ft pounds across most of the range. A $75 rubber TB spacer has been tested to add 6 ft pounds down low. An electric water pump would add 9-10 pounds starting fairly low in the range. Excluding advancing the cam, this other stuff might be $750-$1,000 if you do the work, $750 more if you don't. If your tuner can retrofit an adjustable timing chain, you'd need to add another $500-750 to this to advance the cam.

When you finish all of this get the FAST 90 as your own Christmas present. Yo'll love the mid-range torque! However, it is not the cure for the softness below 4,000.

I understand that this is all off topic, if you really want a manifold. Whatever you do, enjoy it!

 

I have a 2000 frc 6spd, with a car killing set up. if you want fast and powerfull here is the list:

FAST 92 (there is no need for porting if you have under 400 cubic inches it is a WASTE OF MONEY for this particular intake).
FAST 92mm Throttle body
PRC stage 2.5 5.3 heads ported
TSP 233-239 dur cam .595/.604 lift 112 lobe sep.
LG Street 1 3/4 long tube headers
Off Road X pipe
B&B Bullets
centerforce dual friction clutch, pressure plate.
summit 25% underdrive pulley
RAM bullit steel fly wheel
1 mean *** street tune
I put approx 465rwhp and 450rwtq of tire shredding power to the ground in a 3096 pound car. this equates to about 515 to 530 hp on the engine.
Were I to do it again I would go with the TSP Tsunami cam. I dont know if this is the answer you are looking for but I have yet to see anything on the street put me to shame.. I like that fact.
Wait till I install the 3:90 gear set up.

 

Oops I managed to forget about this thread for the past month. I think it's choked for air because that's what my tuner said . I was told it was running out of air and that I was at 100% duty cycle on the injectors. I've got new svo injectors but I was going to wait to put them in until I got a new manifold. The car is no slouch under 4k it just hits like a ton of bricks once you pass the 4k mark. I will look at advancing the cam, I'm no mechanic so I have no idea how to do it but I've got some friends that might know. If advancing the cam could pick up some low end power that would be great! Where would I pick up a tb space? How would a spacer increase power? Thanks!

 

Oops I managed to forget about this thread for the past month. I think it's choked for air because that's what my tuner said . I was told it was running out of air and that I was at 100% duty cycle on the injectors. I've got new svo injectors but I was going to wait to put them in until I got a new manifold. The car is no slouch under 4k it just hits like a ton of bricks once you pass the 4k mark. I will look at advancing the cam, I'm no mechanic so I have no idea how to do it but I've got some friends that might know. If advancing the cam could pick up some low end power that would be great! Where would I pick up a tb space? How would a spacer increase power? Thanks!