i dyno 613hp and my stock allison is still holding up just fine. just depends how you drive your truck and if you understand how your tranny works so you know how to treat it.

 

Then please tell me how! I am wanting to go bigger, but I don't want to fork over the $5k to have my tranny rebuilt

 

I have a good sized efi tune and MY TRANNY HATES ME!!!!! it took me two days before my first "limp" now it limps fairly easily down on the 3rd tune out of 5, be e-z with it mine didn't take that much abuse, but you may never hurt it if you keep it under 3rd gear....

 

Yeah the first three gears are OK, after that you have to be careful.