I can get to the upper 40s in first gear. Not sure what the top speed is in second gear, but it is quite high. Very tall gearing in the 4AT. Its main weakness, IMHO.

 

Then yes, a numerically higher rear ratio will get you to 30 and 40 faster. But like everyone said, your hwy rpms will super suck. The 4.77 might not be too bad, but it will make your milage worse.

Maybe swap in a 6AT?

 

is that possible to get? i want gears to help 1-4 and 5-6 to be nice cruising gears... on the turnpike in 6th gear sucks rpms are always about 4k....

 

Would the 4.77 work on the MT then, and i read somewhere that a rx-8 with intake exhuast, gears and tunned can run mid to low 13s

 

Ok, I am gong to try to explain this. If you get a higher numerical rear ratio, the top speeds in all of your gears will go down. This means you will accelerate faster. This will also mean that the rpms in top gear when you are crusing on the hwy will be raised as well. Therefore this is a compromise.

I think everyone agrees that the 5th and 6th gear ratios are too high numerically, and that the car could benefit esp. from a 6th gear that would let us turn under 3k at say 70 mph. The problem here of course, is that opening up the transmission is significantly harder than swapping a differential.

 

Would highly doubt this. A stock car is about mid 14's car. To drop a car a full second+ with those mods is pretty much unheard of. With intake, exhaust, and tuning you would be lucky to drop .2-.3 sec. of the quarter mile time, and no way that gears would make up the rest.

I would think intake, pulley, hi-flowcat, exhaust ECU flashing, and gears would probably land you in the high 13's, if you are lucky.

 

45mph in first, 75mph in 2nd, 126mph in 3rd, 4th gear is a total mystery to me. I'm slowly reading info about final gears and drives and whatnot in some vain hope of finding something useful to make 4th usable beyond a pure cruising gear. To me its the 04-05' A/T's main weakness, while driving once i shift into 4th I feel like the car is done, A/T or not is not the point. I just feel there should be a bit more omph! to 4th. One day I'll see a thread titled "Finaly a product that makes 4th usable rejoice".

Ok now back to useful info damnit!!

 

What rpms does the AT 4th gear turn at 70 mph?

 

somewhere around 3000 if i recall correctly, for the 4 speed AT.

 

Yep 3000 rpm's 3500 @ 85 mph.
2nd gear 6000 @ 66 mph ( see a commonality here?)