OK.....I'm about to install a BBK CAI. Do I NEED to put a 70 MM t-body on also to realize the full gain of a more capable air intake system, or is it just more toys.....????? BTW, does anyone know the stock opening size on a 4.6 03 GT?

 

TB isnt where the power is to be had and you dont need to install one with a cai. I did the TB and plenum combo and the power gains are minal on a full bolt on GT like mine. I would invest that money in a set of gears (4.10s for an auto) and then save for install and a good tune will make that car alot faster.

 

I had BBK cold air and 70mm T.B. on my old GT and it was okay. You will want to get an upper too. Check ebay and save some cash,used are good and cheap. Its not worth buying them new. Do the 4.10's too

 

My current plans include a BBK CAI and a set of 3.73. I am also looking at the SCT 4 bank tuner chip with selector dial. I do alot of open highway driving (girlfriend lives 75 miles up the road) and according to my calculations (that's a whole other story), with a 3.73 and the .70 O/D I have I'll be about 2750 rpms at 80. I'm afraid of sustained drives any higher due to trans temps, even with the cooler I plan to install. Thanks for all the feed back

 

dont worry about the temps on the highway a decent size cooler will keep it very cool. I had 4.10's in my f150 which has even taller gears then the mustangs trannys and temps were 160-170* in 100* heat on the highway crusing which is very good.

 

stock TB is 65mm, stock upper plenum has a 70mm hole at the TB side. Don't bother with anything bigger than 70mm... and I'd use Accufab or FRPP. Those are the only ones that have always been good to me.

I would just save up and do the gears and a set of lumpy cams. After that you'll get a lot more gain out of the easier bolt-ons.

 

I made a 13 hr drive on 4.10s...13 there 13 back..No problems.