Questions from the new guy.........

[uncreative]

hey everyone,
i just bought a 97 cobra and i'm loving it, but i'd like just a lil more power. i just registered on the site, but have been reading for a while now, so i decided that i wanted to go with some 3.73 gears and power pullies. a buddy of mine has a 95 gt and put 3.73's in the rear and it ran a lot stronger, but ran like **** after a while. he told me to get:
- 31 spline axles
- auburn differential
- ford racing 3.73 ring and pinion set
- rear end rebuild kit
to prevent what happened to his, happening to my car. is all this really necessary? i haven't read a lot about people on this site doing all this. what do you think i need? and where is the best place to get the pullies and around how much will they run me and will i need a new belt? any help would be appreciated. oh yeah, i already have a k&n air filter and an aftermarket maf. i'm not looking to go all out. i just wanna be in the mid to low 13 sec range. right around 13.3 would be perfect. thanks in advance.