I ran 4.30's last season in my Trophy Stock car with a T5. For that class, it seems to be the right gear. You're right though, you're probably grabbing second before you even reach the christmas tree! I've still got the 4.30's in there now with my Lentech AOD and its a pretty decent combination. I'm taching out at about 6400 at the stripe with the 26x8.5 slick. You need to consider the speed & rpm where you want to cross the line as well as the weight & tranny combination...plus a whole lot more.
BTW: The C4 and AOD would finish the same since you shouldn't be using the O/D while racing anyways. Even in a Lentech, the O/D is really HP limited. With either, gear the car so that drive (1.00:1) gets you to the stripe at the right rpm.
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Jeff Chambers
Trophy Stock #3
11.462 Seconds / 117.43 MPH
Chambers Racing Team