Gears are a little expensive and involved, but that's most of the reason it's slower, that and the larger tires are also heavier. 4.10 gears would be an improvement, but it'd be a lot of money for the small gain in acceleration.
The Dynomax Super Turbo is low and throaty, but it's not as loud as some other mufflers. However, if you use the short mufflers like the 17731 you can get at Advance, it will be sort of loud, espeically if you dump it in front of the axle or do a side exit.
You might also consider welded mufflers, either a Thrush welded muffler (same company that makes Dynomax, Advance Auto Parts stores have these in stock too), or a Flowmaster. Listen to audio clips online and see if there are any you like the sound of. Of course, they will sound lower and louder in person, but you can get an idea of the different sound of each muffler design. Make sure you like it, because if it's going to be loud, you're going to hear it all the time every time you drive.