Need To Know Once And For All,,,have A 95 Z28 Camaro,all Stock Motor....a4...pacesetter Longtube Headers...hooker Catback Exhaust..yank 3500 Converter...4.10 Gear Ratio....mt Drag Radials....tune From Madz 28.....will Adding These 3 Inch Cutouts Lower My Quarter Mile Ets...my Best Time To Date Is 13.03 At 104..................my Buddy That Races,,hes Oldschool...says It Will Help By 2 Tenths..

 

With an all stock motor it wouldn't yield as much of a gain than if you had an upgraded valve train. For the cost, you can't really beat it -- you'll see gains, how much however, is not certain.

I know personally with my car before and after the cam with the cutout, you can definately feel the difference with the cutout open and the cam. Before, it was hardly noticeable, you will enjoy the fact that you're noticed much more if you do drive around on the street with it open

 

The previous owner of my car installed a 3" cutout and he knocked a couple tenths off of his quarter with a cold air intake and airfoil being his only other mods. For as little as they cost, it is a pretty effective mod.

 

Since you have a decent catback I'm gonna say on a stock motor you'd likely see 1 tenth tops only because you'd drive it harder cuz you'd love the sound