just a little FYI, if you dyno your car on a dynojet with 2.73 gears and then with 3.73's, with no other mods, the reading will be lower, like you lost some horsepower.
Same will happen with larger or smaller tires as well.

 

I picked up about 1 mph.

My car was stock except for a 2200 t/c, and a stock replacement muffler (cheapest dynomax on earth), I went 13.9@98 before the gears, and 13.5@99 after. This is through stock manifolds w/cats and with all accesseries, including O2 pump. I love the gears and would have done it sooner if I knew how much fun they were going to be.