00 Auto with 4:10

[91LX2Bfast]

Without a shift kit or a chip, your tranny is going to shift "later" because the rpms are rising much quicker then with your stock 3:27's.
Lets say that your car commands the shift to begin at 5600 rpm with the stock gears, and by the time it actually makes the shift, your engine is around 5950 rpm. Well, with the 4:10's, it'll command the shift at the same 5600, but the rpms are rising so much faster that the shift might not occur untill 6300 rpm.
Did I explain that ok?
So a shift kit or chip will make the shift occur much quicker and firmer, and the engine rpm will be back at an acceptable spot once the shift is finished.
Fell free to ask more questions because I am not sure if I fully explained it.