My dads best friend has a pretty nice 347 in his convertible, has Dart heads, large cam, Performer RPM, etc..etc. This was when it had the smaller headers on it. With the high stall and C4 it puts down mid 300's at the wheels
[ame=http://www.youtube.com/watch?v=mBUOzbPNqe0]YouTube - Jim's Mustang[/ame]