djb1187

my car is n/a and i benefited slightly. go ahead and get a 75mm you wont be dissapointed

jpmustanggt

Just get a 75mm

oxfordgt

You can go as large as you want as long as you dont go larger then what your MAF is. Bigger is better.

ben790450

Bingo

cliffyk

If you look at Accufab's flow data (click here, about 1/2 way down the page) you'll see that the 75 mm TB only flowed signifcantly better on the C&L plenum. On Accufab's plenum there was no advantage at all, on the TrickFlow (same as Pro Products) the 70 actually flowed a bit better--that's why I got a 70, even though they cost the same.[/align][/align]I have also seen many references that if you ever go FI a 75 mm will be too large, though I have no direct knowledge of this...[/align][/align]

djb1187

i dont see a 75mm being too large on a blown GT. If anything it would be way mroe beneficial

Sap

I'm blown and run 75mm TB, works great. Even if your not blown, a 75mm is the way to go.

E.

undecided.steve

http://www.yellowmustangregistry.com/cnl.html

70mm vs 75mm Throttlebody:
We also tested the 70mm vs. the 75mm Accufab throttlebody since we had heard complaints that the 75 was too large of an opening. For our testing, we proved that to be FALSE. The below graphs show 3 runs including our best run with the 70mm, our best run with the 75mm, and then the 75mm run after tuning with the Optimizer. This graph shows that when we went from the 70mm to the 75mm the horsepower and torque stayed nearly identical, but the A/F ratio dropped. Which means there was more airflow but the drop in A/F caused a rich condition but the car still produced more power. After we tuned the Optimizer to get the A/F ratio back up, the power increased beyond that of the 70mm.

Take it with a grain of salt, and also note they installed some other parts as well at the same time.

One point of interested is that Ford Racing sells a 70mm but not a 75mm TB.

Personally, I agree with the statement that if you are going FI get the 75mm.
I would 70mm otherwise or at the least, get an A/F measurement if you install a 75mm.