from these mods:

Z tube with K&N filter
JIC Y-PIPE
Kinetic High Flow Cats and Plenum
UR Crack Pulley

 

I don't own a G, but if I were to sum it up with Z gains I'd say u'd get a nice 4~6 rwhp from the crank pulley all thru the powerband. I definately noticed that diff when I dynoed my car. From Kinetix plenum/cats I'd assume you'd get around 6~10 rwhp but definately more area under the powerband. It's a little conservative a guess since there really isn't much info out on them yet. I have no idea about the Z tube or Y pipe since I went true dual. I hope this helped. Take it ez!

 

You'll get gain's, but until you pair the Jic Y-pipe with a 80mm system down stream, your holding it's full benefit back. Suddenly going from 80mm to 65mm is the problem. Kinda hard to say what you'll get since people tend to be all over the map come dyno time. If you have a good day at the dyno you'll get 15-20hp.

 

The Kinetix tandem was good for 17hp on the dyno that I saw. The others mods should add a couple of HP each, but I think that CRACK PULLEY should be good for a "butt-load".

 

i say 20-25