Just a little testing I did at the track(pavement). I ran it at the 1/8 mile this past weekend jsut for fun after running my truck.
1st pass- Launching in 1st with my mods slipping the clutch and leaning with my head and body over the bars I ran a 8.68 at 72mph with 4lbs of pressure on bald stock tires.
2nd pass-Now leaving in 2nd against my friends modded 04' mach 1 mustang I revved to the top and went half way out until it was moving decently(5/10mph) then let it rip. 8.46 at 75mph.
3rd pass-Tried a differnt launch this time leaving and slipping the whole way out in 2nd and ran a 8.50 at 74mph. Felt really slow out of the whole and people watching thought it was a very weak launch.
4th pass- Got ballsy and dumped it in first about half gas.....

hit 2nd bumped the grab bar, hit 3rd once again tapped the bar, hit 4th came down about half way hit 5th gear and came down and ran a 8.93 at 76mph lol.....
5th pass against my friends 72' chevy built 355stroker on spray and street tires.....

2nd gear launch from full throttle wheelied a bit hit 3rd wheels came down and ran a 8.39 at 73mph!
Now I know I'm not the best rider in the world but have quite a bit of experience just not much at all on this quad and feel that with more passes better times could be pulled before more mods..... did however beat a modded banshee on the last run of the night 8.42 at 75mph and loaded up feeling pretty happy!
My personal experience is I'll launch in 2nd on hard pavement and on hardpack trails, havent had the chance in sand or similar terrain. An extended swingarm would definately come in handy!