From just a muffler or a catback over the OE exhaust?Or an ET comparison? Smoke?

 

Here's a dyno sheet for ya...MODs are...
UPD cold air
ASP pulley
ASM headers
PrescribedPower camshaft & tuning

http://www.prescribedpower.com/images/HRTRUCKDYNO.jpg

 

In reality not hypeup ads, you are probably looking at 7-14rwhp. I just don't see it being anymore than that as stock exhaust systems are getting pretty good today...but still have room for improvment.

Usually for looks and sound they are done initially. After a while they become an important part of the efficiency of the motor as power levels are increased.

 

I agree with hitman x. In fact I think you would be lucky to see 14 rwhp, 10hp would be more likely.

Hey ISSPEEDWS6 do you have any dyno charts of that 03 before and after the cam? Just curious why that truck is making so much more power than my truck when the only difference is a cam and pulleys? That is unless the cam/pulleys accounted for a 40-50hp gain.

 

That ASP is good for 7-12rwhp, a cam will easily yield 25+ rwhp if not more...but that all depends on duration and such. I believe someone on here did a 212/218 and scooped up ~30rwhp.

So that is easily attainable...headers only make a cam work better also.

 

That dyno sheet is the before and after of the cam install and tuning.The 330# on the base line is becasue i got to start with a 2002 ls6 engine.
The 389 was a result of the cam,headers, and asp pulley.

Truck still has mechanical fan, factory CATS and Y pipe, 20 inch wheels that weigh 76 pounds each.This IS a manual transmission truck....6 speed actually...has 3:73's for now...going to a 4:56 i think...