Alright I did do sum surfing here and found a lot of questions anwsered. I found out that mine is a GU5, so what 3.42's? Anyways, what would be the problem in slapping on 4.10's on an auto? Like would it kill my baby? What if I were to get a new driveshaft? I mean I wanna go big on everything with this car. And where's this performance switch or whatever I read about? I wanna go faster, totally obliviating all other cars. Even the 5-0. jk

Check out this website. It will show you what changing the rear axle ratio will do to engine rpms in all the gears:

http://www.f-body.org/gears/

If you change the driveshaft (a good idea if your car came equipped with the OEM weak unit), you should consider mild steel, 3 inch diameter tubing with hollow yokes. It will weigh about 1/2 what the OEM driveshaft weighs and be a whole lot stronger. You can have one custom made for your car by any number of companies that advertise in the backs of car magazines and on the Internet. Postage costs about 20 bucks via FEDEX or UPS--total cost maybe $250. Make sure that it is balanced to at least 3,000 rpm and the yokes are hollow to save weight. This is the link to the guy that made mine:

http://www.drivelineshop.com/

GU5 is the RPO for 3.23's not 3.42's

Anyway doing a gear change wil dramatically inhance your acceleration as long as you can get traction. Generally most auto equipped cars perform very well with 3.73's. If you don't think that's enough 3.90's would be the next best option, IMO 4.10's are too much for an Auto equipped car with a stock redline.

What is the RPO code for 273's?

GU2 = 2.73
GU5 = 3.23
GU6 = 3.42
G80 = Limited slip differential.

generally speaking, 4.10s are too much for an auto and you'd really sacrifice fuel economy. Because of where an auto redlines, and the fact that it only has 4 gears makes 4.10s a little too much overkill for most people. Your RPMs would be way up at highway speeds...

GENERALLY what people go with are 3.73 gears if you have an auto, and 4.10 or 4.11 if you have a manual...

and I believe 4.10s you'd have to change the carrier ion your rear diff, and idk how hard that is.

as far as driveshafts go, Ive hard and seen(at the track and on youtube ) horror stories of aluminum driveshafts...theyre lighter, but weaker...however, like Me Too said, itd be a good idea to get a stronger one...

they also make carbon fiber driveshafts...but im not sure about there durability but i bet their real light but also pricey...

3.73's will be more than enough for your car. You will be thown back in your seat MUCH easier, and you'll be spinning the tires through 2nd no problem. Don't go with 4.10's, those work much better on the M6 cars. The 3.73's will go right in and all you will need to do is adjust your speedo for them. A tuner can do it for cheap.