ok, i'm looking to beef up my 08 mustang gt 5r55 automatic tranny to the street fighter 5r55s tranny from "peformance automatic" Transsmission or the 5r55s from " T.C.I."
anybody know about that paticular tranny ? is it a pretty good one. i'm getting ready to do a u/d pulley change, with a new tune, up my boost level, my stock tranny will not handle that. so, i have been looking at this super streeter 5r55s it bolts right up to my stock. any feed back will help me make a determination. thanks.

 

Just use your stock 5r till it gives up. I'd get the transmission that exceeds your engines power level. While you swap transmissions get a torque converter from circle D. They make the best ones and go with a multidisk if you desire to keep it as a lock-up.