So does it hurt the transmission to switch in and out of D and 3 when already on the road? Or must this change be done at a complete stop each time?

You can shift while moving, it won't hurt anything

I like to dig out of 1st and go through the gears the few times i ever race. From a roll i'm usually in second though.

so wait, i can put it in 3rd instead of drive, and it will shift up to 3rd and this is better if im racing and using wot??

Yes, that way you are locked out of 4th gear so it doesn't accidently shift into it.

Also in Overdrive the car wants to shift earlier, 3 should hold longer.

Depends on your WOT Trans tune of course.

Going to have to try 3rd instead of 1st from a dig

So if your engine is all stock, is wot in 4th gear still hard on it? I'm just curious.

Yes, 4th gear only has 2 frictions for clutches, they don't like seeing power pulls. Stock you will get away with it for a while though still hurting it slowly. The more power you make the quicker the damage happens

I did a 3rd gear pull with some buddies the other night in Mexico and it felt so weird to leave it in 3rd, usually once the rpms got high i would throw it in drive. Also i tried a dig from 3rd and it felt so weird but it did pretty well. I was impressed