yeah, I have the RB 323. Insane power, keeps it's tune and if it does go out it re-tunes easily. Whole kit takes about 45 minutes to install. There are two mistakes in the directions but they are easyto figure out. Whole kit has everything you need. Buy it at Rob's R/C Hobbies, 714-372-3777, for 219.00.
V-Spec might make more power but I have had troubles.
VB, my problem is having it hold a tune throughout even a practice session. I sealed the carb and backplate, use 30% Byrons, factory turbo plugs, everything. It just seems to lose it's crackle after a few minutes and gets boggy. Doesn't stall, just loses it's tune enough to cut into the power.