13/36 will put you close to stock speed... Its just a hair faster. 14/39 does the same thing if the 36 turns out to be too small.

13/35 is probably pushing the clearance factor, so if you want that kind of speed you may have to change the front to 14. If you don't accelerate fast, then it doesn't matter anyway. But if a really snappy quad is your goal, I'd shy away from the 14. I don't know your riding style. Its been my experience that a little change in gearing makes a bigger difference on the trail than you'd think.

 

I'll take your advice and work off the 39 but for the most parts its just trial and error and sticking to what feels best.