I tried a 87mm GT350 throttle body after I got the correct adapter plate to mount it to the stock intake, but the tuner I chose could not get the car to run correctly. So I put the stock 80mm back on and I'm waiting for approval from the third party seller on amazon to return it. If it gets approved, I'm going to get the ford racing power pack #2. It comes with the GT350 cold air intake, 87mm TB, the adapter plate, and a 50 state legal tune direct from the ford engineers so it will run correctly. The going rate for the #2 power pack is 800, I tried to go cheaper by getting everything separately, but I ended up spending 550 and it didn't run right. So, you live you learn. Also Late model restoration did an install and test of the ford kit and got 26 hp at the wheels on a manual car, ford only claims 21 rwhp, so 800 is not bad for approx 30 crank hp. The general rule is a 12-15% drivetrain loss with a manual and 15-20% with an auto.