Hey everyone. New to this forum, slightly new to Mustangs and cars in general. I completed a GT40P swap a week ago, runs awesome, a lot more power. I am getting BBK shorties to help the plugs clear a bit better, and was wondering if a 70 or 75mm TB put on at the same time would help the car breath much better and what I could expect from the two? Here's my current engine mods: CAI GT40P upper/lower GT40P heads B cam Underdrive pulleys SCT tuner New distributor, plugs, wires Thanks!
Throttle body Go with the 70mm over the 75mm. You potentially would have enlarge the opening in the adaptor elbow [supposing you haven't done a fox throttle body swap yet] for the throttle blade to open without interferance. You most likely will see a slight increase in power, less than 5 or so. You may also run the risk of a surging idle and other driveability issues without a tune. Some cars are excellent patients and you can get away without a tune but most, like mine, get all :handz: and won't run right. Headers Anything is better than the dinky, restrictive stocker headers and you should feel a bit of difference depending on your other exhaust mods. Don't be surprised if you lose a little torque down low to gain 5-10 hp [generous estimate] in the 3000-5000 rpm range. Best way to fix this? GEARS!!!!
I have 3.90 gears, so that's not a problem. First gear is burnout gear now! I also have a full exhaust. H pipe and SLP LM1s.
Welcome to the madness you will still have a problem with 1 plug with the BBK headers. but it's not anything that can't be overcome. FRPP and MAC both make P specific headers.
I got a really good deal on these I couldn't pass up, I read they have more clearance than the stock headers so at least I won't have to worry about burning plugs I think?