Okay, I'm sort of sensing a conflict of interest here. Meaning this: you are running power for a drag racing car. So auto is probably the way to go. But yet you are talking about Auto-X, so I'm not really sure of your goals. (Plus, 1000 rwhp for an Auto-X just, frankly, sounds like a really bad idea - if you are going to road race it, jesus christ, you better have god's own suspension on that thing and god's own feet for your pedal modulation. Talk about a scary ride :dread: ). Now, for a drag car, okay 1000 rwhp. I get it.
I think I'd break it down like this:
- If you are going to drag, then for sure auto. With as many gears as you need to be top end at the end of strip. If you can do that with 1 gear, then do that. 2 or 3 gears? Okay. The more gears the worse, you don't want to shift in drag racing
- If you are going to auto-x/road race your car, then you will want more gearing to take advantage of the various speeds on the track. The more gears, the more close your ratio's can be, the better. Talking about 6 speeds here - most likely manual. Although, you might be able to find an "automatic" (as in no clutch pedal) trans that's shifted manually, a la rally cars, etc. I shudder to think of the cost though.
- If you want to drag race and road race, then....I guess pick which one you want to be worse at, and pick the trans for the other one. There really isn't a compromise, especially not if you are talking about that level of power.
For what it's worth, RichV (I think it was RichV) posted a vid awhile back of a bad ass Mustang and a GT-R going at it on a road race track. It was magical. The Mustang had, IIRC, something like ~700 rwhp. And it was a monster. Literally. It was balls fast, plus the driver, who must have been very skilled, was doing all he could to keep that car on the track. I'm talking balls fast, like in the straight it just walked away from the GT-R. Pure magic. And that's with something like ~300 rwhp less than your plans. Your car, with that much power, on a road race track, I have to imagine would be very difficult to drive. Just food for thought.