Stewart, radial tires shouldnt grow... bias-ply slicks will though. normally a little over an inch by the end of the track. I would do the 4.56's for your setup and never look back IMO.

 

my truck just always seems to be in the sweet spot now, roll racin from about any speed, dig racing is awesome...all assuming you have sticky tires though, which you run nitto radials i believe so you should be ok

 

i dont really care about my top speed on my radials. no need for me to be going any faster than 120 on the streets. just looking for top speed on my 28x10-15 mickey t tires. im getting the truck on the rollers next weekend to see where it makes power. ill make a choice from thee

 

Here cool excel file that download from here. I think blackgmc make this one. If you shiffting 7k in third gear it will be 136mph. Here you go.

 

mine the dyno in 3rd locked did 127 at 6200 on a 30" tire

 

the file you posted comes up as corrupt russell. thanks for the answers guys.

 

not what the thread asked for..but with my 4:10's and a 29" tire i hit 121 at 6000..not sure how accurate that is tho..cuz i had a friend in a sport bike tell me what i topped out at lol my speedo stops at 100

 

Try this.
https://www.performancetrucks.net/fo...d.php?t=396210

 

Damm i didnt know we could go that fast with a 28in tire, iv never gone past 110 with mine im to scared my drive shaft will fly out of it, buddy of mine did that at 140mph once.. i dont want that. and a 250 shot at 7k on the top of 3ed gear!! You have alot of faith in that ls1.. i like it!

 

i have the 2 piece driveshaft. been past 130 tons of times and past 140 a couple. 2 piece driveshafts dont have the issues that the 1 piece and aluminum shafts have.