I currently have 4:10 I run 26 inch tires for street and 29 for track. Ive got lots of top end but get tired of buzzing 3800 on the highway.Car runs mid 11,s would like to switch to 3:55 what will 1/4 mile times be like? as well as cruise speed at 70?

bb485-
just a suggestion but maybe you should just switch to an overdrive tranny? then you could have an even better takeoff since it has a low first gear and low cruising rpm due to the overdrive. i think one day i am going to swap from my th-350 to a 4L60E (oooo electronic :D )
btw are you running and 8.2" 10 bolt by chance?
-jay

You should only give up a few tenths at the track by switching to 3.55's..maybe less if your combo isn't optimized..

Jay I just switched from 4spd to turbo 400 and I have a 12 bolt.

3,211 RPM's @ 70 MPH with 26 inc tires & 3:55's.

Go to the web sit (ringandpinion) then go to (Randy's Ring & Pinion) site rpm calculator
if you want to check out any more gear ratios for curise rpms on the street.

Scott