Vinny - go for the 65, will really help maximize your headers. Just keep in mind when switching to either it or the SVT unit, you'll need to get the SVT throttle cable and bracket. You may also want to consider going with the 80mm mustang maf, and 19# injectors. I run those with the 70mm TB on my 99 Cougar, and they work great. Mileage is up noticeably as well.
Hth,
Dan Beggs
99 Cougar V6, loud
