i was wondering which bold on aftermarket part will give me the most "bang for my buck" or in other words the most horsepower gains, i was thinking test pipes but i dont know...any ideas?!

One of the best bang for your buck mods is the Motordyne Plenum spacer.

http://www.motordyneengineering.com/...a64d982046581a

Consider getting a new exhaust system!

i 2nd that!

Spacer, Test pipes, Z-tube, High flow filter, Y-pipe, Tune. DO all those at once and have a smile on your face

You'll see an increase in power with an aftermarket exhaust, but the MD Spacer is much less in terms of $ per hp.

If you have a coupe, buy a plenum spacer first...if you have a sedan get rid of the 100lb exhaust system first lol

Perfect....^....MotorDynes spacer has always been the best investment for our first gen G35s. In addition and keeping it "Legal" replacing those restrivcive OE cats with HFCs are the two best "Bolt On" mods!
Gary

...wait for it.......

would this fit on a g35, Motordyne Mrev2 Lower Collector?

^Yes

Used Vortech kit.

5/16 Motordyne spacer, art pipes, and motordyne exhaust!! Add an oem z tube with revup oem intake box with a k&n drop in..

Motordyne plenum spacer and HFC's both give you a better feel in the midrange!