C4 won't hold up to the abuse and the glide will do unless he plans to still drive it on the street. The 2 speed is no fun for that.
Look no further than here for a trans Jeff:
http://www.rosslertrans.com/
I have been doing a bunch of research on C4s', TH400's and 4R70's. I will go with one of them.
Sold
2004 Cobra, Whipple ,TH-400
Burning Corn
9.97 - 135.5
I priced out a C4 for my 88 Turbo car and it ended up being almost the same price as doing a TH400. The TH400 will be the only tranny you'll ever have to buy if you get one that's done right.
its one of those things where a turbo 400 just eats more power, while a manually shifted c4 auto will take less. and we all know jeff likes to go fast lol.
ill PM you a link jeff
2005 v6 redfire mustang. yup its slow.
12.03 @ 118.5 best et
12.11 @ 122.0 best mph