Would using B & M trick shift in '11 gt, auto trans, void warranty?

 

i wouldnt use it. it doesnt withstand heat as good and it ends up as gumps inside the transmission if you dont change it more frequently. if you want firmer shifts get a tune and just take it off before you take it in for warranty.

 

Wouldnt they still be able to tell if the ECU has been messed with though?

 

they probably could. i know gm can but not sure about ford. they dont normally check to see if its been flashed i know that tho. i had to get my transmission replaced and i had a tune on mine at the time. didnt have a single problem.