How much gain with lower gears?

roccodart440 said
As much as a half second. My car goes 12.20's in 4th gear. 11.70's in 3rd gear.

What you want is a gear that will put you through the traps at about peak hp RPM. If you don't know what RPM that is you are pissing in the wind.

Also keep in mind where you want to be at cruise RPM. Balancing street and strip without an OD gear takes some conservative thinking.

3.55's will put you at about 2500@ 60mph with a 28" typical tire. 3.73's will put you at about 2800.

I'd be running 3.55's if I were you. Or a GVOD and some big ole gears......

This is correct. You also need to look at your cam specs, most cams are made to use a certain stall convertor, motor compression and gear ratio to work together. Once you have this set up and some track time, you can change one thing at a time to see what works better. Like gear ratio. I run 4.10s, I go from street use, right to the track. With just by changing tire pressures. But I also lost some street ability because of RPMs and ride comfort with my suspension set up.