125shot NOS kit for EFI Mustang and the computer takes care of the timing retard. Realize if you go this high, it will be really hard on the tranny and rear end. Definitely use synthetics everywhere and change them frequently. ZEX has some of the better kits out there now. 75 dry shot will be fine - any higher and I’d go with a wet kit. Disconnect the front end and you will light those rear tires up!