OK Beach, I guess we can keep your advisor on "retainer"...hehe
Seriously,
If you're going to go with new mufflers, I'd personally go with a full cat back system. Not much more expensive at this point, and you'll be ready for that new X\H-pipe when you've got the cash...
As far as removing the air silencer, different dyno tests have shown different results... Some have shown a slight increase in power, while others have shown a slight decrease....
It's actually somewhat of a debate and one of those things that proves what might be good on the ol' 5.0, may not be the same for the 4.6...
I think that the stock gears for a 2000 auto GT are 3.27s.... Not sure though....