I would love to get a rear end form a VT or VX and mate it to my GrandPrix but that will not happen.
If I had that car I would go to
www.delcohacking.com and find someone that has the equipment to burn the ECU or start doing it myself. Checkout the address and see if anyone can help program the computer if so you should be able to modify the turn on points for lean cruse and the running duration of it along with shift points. I'm not sure what all is available on the ECU to be edited since it is a OBDI setup.