70mm throttle body question

you will not gain anything with the tb alone. We did a dyno of the FRPP TB on my 1998 GT with PI heads at 264rwhp, we gained nothing, so I went back to the stock one. This was back in 2001, so the plenums were not part of the equation then.

I wouldn't say you're not going to gain anything with the TB alone. It just won't be much, and it may not be in the RPM range where you normally drive day-to-day. You may see a gain of 4-8HP but it may be in the upper range of like 5,000RPM or higher.

I DO agree that porting the plenum isn't going to make a difference either.

You'd probably see some good change with a custom tune after the throttle body install, and that's what we'd recommend. If you have the car dyno'd after the install, be sure they test it at the higher RPMs (if you're comfortable with that).

With this model though, you'll probably get the highest HP gains with a Cold Air Intake (which you have) and working on freeing up that restricted factory exhaust flow (if you haven't started on that already). I just checked with our tech/sales guy and he agrees.

You don't need a dyno tune. Leave the stock tune until you upgrade the heads/cams, or add gears.

Most likely, the HP/tq increase will be from the increase in timing.