Depends on a lot of things. The higher compression that you go, the less injector you need. You can also go with a higher static pressure to lessen the load on your injectors.

If you don't want to get stuck at around 400 whp, I recommend going with a 650 (RC measurement): http://www.wiredspeed.com/itemdesc.a...%2D650&eq=&Tp=.

Axle replacement in a nutshell: https://www.honda-acura.net/forums/s...d.php?t=173647

Good axles: Gator (if you get the right 'stage'), Enjo, Raxles (so I've heard), DriveShaftShop, and a few more...
Be prepared to spend a pretty penny on axles though....