Damn see such a wide array of numbers, this has a good sized impact on aftermarket mods. If our numbers truly do lie that low might end up looking at 5.7's.

 

I wanna know how much mine will make with headers, exhaust, redneck ramair + drop in K&N, trans dapt throttle body spacer, and a custom tune to the wheels. I think with all of that it probably won't get much more than 240hp-250hp to the wheels. It sucks but that's the reality of it. The thing is though that everyone elses power to the wheels is also drastically lower. So in a racewhat it really comes down to is the individual truck. Even with a mere 250hp to the wheels, my truck is so light that it still has the upper hand... once I get headers and a tune that is

 

I have to find out where I read it, but before I bought my truck I found a web site that ran through the history of the GenIII LS truck motors. The first 5.3 (99') was about 275hp, then in 2000 it was 285hp, then 2001 and up was 295hp. The 4.8 in those same years went from 265hp (i think) in 99' to 275hp in 2000 and 285hp 2001 and up. I could be wrong about the 4.8 in 99' but the rest should be correct. The 5.7 and 5.0 Vortech motors were pretty consistant throught the years, I guess they had to fine tune the 5.3 and 4.8 over the years. The weird thing is that not much changed in the 5.3 internals which makes me think I would have been able to make the jump from 275 to 295 with just a good programmer (Like anything other than Hypertech, lol).

 

Variance in hp can be caused by many things, what type of dyno, elevation, humidity, temp, fuel used, the engine itself, and flywheel or ground. '06 5.3L came with 3 different ratings from the factory based on which 5.3 you had. there is a 15 hp difference between Flexfuel and standard. I don;t think anyone here has a Hybrid, but they are limited to 320 tq.