Looks like you figured out the avatar...
I think the stock gear ratio is 3.27....
(not sure on 2000-2001 models)
A 3.73 gear ratio will give you better acceleration as you'll get in your power band sooner, and a much needed kick in the pants in the lower revs...
Some folks like 4.10s but if you use your car as a daily driver like me, I think the 3.73 ratio is a better choice for standard transmissions. There will be a very slight increase in fuel consumption, but to be honest, I didn't notice any increase in my monthly fuel spending....
The short throw shifter not only enables you to make quicker shifts, but more importantly, more RELIABLE shifts. Nothing's worse than hearing that GRIND when you're trying to toast some rice....
Pulleys are the objects that your serpentine belt wraps around in your engine compartment. (usually crank, alternator, and water pump)
Horsepower pulleys give less parasitic loss from the horsepower your engine puts out... while theoretically extending the life of your accessories...
(Sounds like a sales pitch to me)
Mustang92 is correct about the blower application. If you are going with a blower anytime soon, you'll need to use the stock pulleys.
For more info, go here:
http://www.mustangsplus.com/mag_ad/page17.htm
Have fun...