I was browsing the GMPP catalog, and was trying to guess how much extra power will each bolt on add, as well as how each stack up with each other.

Of course we have the GMPP Air Box, GMPP Shorty headers, GMPP Exhaust.
These are my guesses for the parts:
Airbox: +5-10 HP/TQ
Headers: +6-12 HP/TQ
Exhaust: +6-12 HP/TQ

Of course with multiple bolt ons, they help each other out, so with all bolt ons on a LS3, i would say it would add around 25-40 HP/TQ.
Any other guess, or are there solid numbers yet?

 

I would think you will get more than that from headers with that combination.

 

I think many up here will tell you that shorty headers don't give you anything except a
nicer look. I have seen this stated over and over again. I can't wait to see some real life numbers to see how much all of this gives. I would love to get your estimates.

 

texas perfomance and machine has been testing their new headers for the SS and has posted some pre-tuned numbers.

 

So has Hennessey performance. I am in that same camp on the shorty headers. I don't think you get anything but a slight power curve change depending on design. You will get a gain,just not noticable.