its an 07 with BBk CAI and Single Flowmaster. what gearing should i get? 3.73 or 4.10? is there much difference in mpg loss between the 2?

 

From what I've heard, I'd go with the 3.73s.

 

3.73s will loose 1 mpg on the highway, 4.10s will loose you 2 mpg on the highway, city milage will stay about the same

you mise well get a detroit true trac LSD or an eaton, or swap an 8.8 in with those gears.

 

It depends on your plans for the car. Naturally aspirated or forced induction? Daily driver or occasional track car?

If the OP is just wanting more grunt for a daily driver, then he could install a Ford T-Lok at the same time as the gears instead of the more expensive LSD's you mentioned. But if he plans to hit the track at all, then your advice is spot-on...

 

Agree to the above

and a common saying is "Don't Fear the Gear." If you plan on staying N/A, go with the 4.10s. If it's too much, you can always compensate a little with a taller tire. But I think you'll like the results.

 

just go with 5.12s and a full spool