spears are already very heavy. Mine had an overbuilt fuse, way to much resin IMHO.
My super sniper did 155mph off 1400 watts. Technically it would take +3300 watts for the same airframe to hit 200mph. I had the the composite super sniper with the fully molded wing (I.E. it wasn't going to fold).
With some aerodynamic tweaks (no servos sticking out on the wings, smoother intakes, etc etc), and the right power system, I think 200mph with a sniper is possible.
I've run a few 70MM's to +3000watts. Only DS-30's will take that abuse, and even then sometimes they won't. I spun the center right out of a DS-30, with one of my 12S setups.
The butter zone is right around 1900-2100KV, for 10S-12S. About 80-90 amps depending on load. I used 3S 2100 40C batts. These days you can get 55-65C batts no problem.
The only motors I got up to 3KW with any kind of reliability were the HET 2W-30 (only in very short bursts, on 11S), a Neu 1115/1.5Y(12S), and a Mega 16/40/1.5R(10-11S depending on batteries).
Those all spin the DS-30 to around 75K RPM. Trust me, it's a hell of a noise.