how much power is the stock t-45 in a 99 gt able to handle?

 

I think its around 400 ft lbs of torque.

 

People break them with stock motor and some guys push 500-550ft lbs and launch them at the track and they last. Its a crap shoot.

 

They're rated at 330 ft-lb.

 

The shop that just rebuilt my tranny and clutch told me the same thing. he said he's seen guys beat the crap out of transmissions and no problem, while others spend a day on the track and need a new one.

 

They last proportionally to how you use them. You can put 350rwhp down all day long and have it be very reliable but that means you're not launching hard or power shifting or doing lots of nasty burnouts.

I fragged the stronger tr3650 3 times in the first 20K miles beating on it. The 3650 I have now has taken more abuse than all 3 previous trannies and seems to enjoy it.

Logic + experience says it's a crap shoot so be conscious of that as you whip on it.