Ford Racing is soo much better imho.
$600-700 depending upon where you get them installed, My shop told me 9 hours! But i only paid $400 because i send them a lot of business... But be ready to listen to the whine of the new gears, they almost never are quiet on most cars ive seen with upgraded rears.
Also, the 3.73s really arent noticeable if you have 3.55s... but if your stock 3.23s, then you will notice a slight change. I was expecting a drastic improvement, but it really didnt do too much.
And about your launching... If your launching your car as fast as you can and spinning tires, then your not going to notice a change. Increase in tire speeds will cause you to break the rear end loose. If you have no traction problems all ready, then yes, you will notice a better launch.
2003 Oxford White Mach 1
T-56, H&R Lowered, Crushin fully built race cars in autocross allllll day longgg