quick question, my car is an 86 IROC 305 TPI, 3.23, auto, would 3.73s be too much for it? ive got a mild cam, full exhaust, all free mods. Thanks

 

these will help but it will increase your rpm in top gear & lower your top speed. Not to mention less mph per gallon--rock on!

 

I had the same drivetrain combo when I was an auto and it made a huge difference in performance, car launched harder and faster, went .5 seconds faster in teh 1/4 and gained 3mph.
you should still be able to hit 140mph in 4th. mpg may suffer slightly, but when you build a fast car, mpg shouldn't be too much a concern, if it is then you should get an econonbox beater.

 

Throw a t56 in front of the 3.73 and with the .5 overdrive in 6th you will wonder why not a 3.90.

 

T56 and 4.10's, that's the combo.

 

Typically a TPI setup will not make any power in high RPMs so you would want to keep a high gear (numerically lower) as to not keep the motor out of its powerband.

But it all depends if you want to try to do 500mph top speed...

 

Well im not really concerned with going 150 mph, i just want something thats not gonna run outta steam in the 1/4. More than anything, i just wanted to know if it would make it noticeably faster stoplight to stoplight.