If you have a spare grand laying around (well 1300 or so if you want the CT dif housing like I got) do yourself the favor and order the 4.77 gears from hardtopguy. I haven't fully broken them in yet so no hard shifts, but here's the breakdown:

1st gear - Shorter time until redline. You won't feel that much different in the pants but get ready for 2nd gear...

2nd gear - You no longer have a 4 cylinder car, you have a huge V6 with gobs of torque. Second gear winds out really quickly and you feel like you have a completely different car. I'm not talking about the little extra push you get from 4.57 gears, it's almost like you have a small amount of boost. The car feels about 3-4 hundred pounds lighter also.

3rd & 4th wind out so much faster. They are kind of intermediate gears now and you don't want to really cruise in them. If you're driving slow around town, you'll only need to start in 2nd gear and quickly get to 5th or 6th.

5th gear - This is more like how 4th is with stock 4.1 gears. It's a good around-town cruising gear and a great choice when cruising on highway if you want a quick accell boost to pass a car.

6th gear - Admittedly, your RPMs will be a bit higher here. On the highway, I find that I cruise slower now to keep the revs down, thus reducing the chance of speeding tickets This gear is like 5th gear on stock 4.1 gears. You'll easily be able to accellerate in any speed here and not have to downshift to really pass anyone.

Overall, 4.77 gears make your car SO much faster than stock. Scared of the new ION Redline and Saturn Sky GXP? Worried that you may misshift and be embarrassed by that cocky 350Z driver? Want to keep up with cars you never could have before? This gearset will make your car accellerate so much faster, I just cannot give enough praise to them for only a grand-ish from your bank account. THIS is the mod that all of you N/A freaks need.

 

Sounds almost like an advertisement.

What RPM does the engine rev to at 70 and 80 mph in 6th?

 

Thank's,but no thank's;I'd rather keep my 4.56 gears.

 

I'm afraid not everyone have your same sentiments and not everyone should get them:
https://www.s2ki.com/forums/index.php?showtopic=389458

 

4.57 are fun but still not enough thats why a SC AC is needed

 

Gears make a bigger difference with AP1s than with AP2s, right?

Why did you install the reinforced diff if you're not supercharged/turboed?

 

so he can launch without breaking the diff

 

^ bingo

And yes, popping through the gears is important in any situation but that goes without saying.