Even on a relatively stock car, which I have HFC, xpipe, AA filter and 95 octane, 1st gear is useless as spins the wheels easily and is no good. Gears would render it completely obsolete. Second has great thrust and can hold it to 66mph, rather than gears which lower it to 57mph. So ultimately what you get is useless gear 1, bit more torque throughout second but it lasts a shorter time and a bit more in third but lasts significantly shorter amount of time before shifting up.
Depends totally on where you drive and how you drive. If you use higher gears a lot like 4 and above than they can help with torque. If you play arond in 2nd and 3rd, the OEM gears allow you to have a wider power band of speed to maintain the full thrust and torque multiplication of 2nd gear and 3rd gear which are far more important than the minor increase from a new diff