ok so i just recently did a engine and transmission swap on my mustang gt. i had a 97 gt and i installed 3.73 gears and it threw my speed off by about 10mph no big deal i knew i could buy a different transmission gear and it would fix that but i let my cousin borrow my car for month while i was out of town and he blew my engine so i did a engine swap and i put a 99 gt engine and transmission in my 97 body. well after finishing and taking a test drive now my speed is off horribly i will be in first gear doing 80 shift into second and now it says im doing 150mph so its not even close and i know you can not buy a transmission gear since that changed in the 99 but american muscle makes something but it cost $140 but everybody is complaining it doesnt work so im not going to buy it and waste money. so does anybody know what i can do to fix this and get my speed back to normal or has anybody bought this from american muscle and it actually did work.
what does American muscle sell that everyone says does not work? pretty sure you need to get a hand held programmer. American muscle has the bama tuners, and i have never heard anything bad. hope this helps.