how much power will the 48re handle before it starts to slip and cause problems. Is it as strong or stronger then the Allison??

 

Depends on how heavy your foot is. Most will handle an additional 50 or so HP but it's usually the torque that kills them. More power usually causes a heavier foot which causes broken parts. The 48RE is as good or better than all the other stock trannies are. If you mod the engine you need to mod the tranny also.