I'd guess 136x1", FWIW. Should be enough track unless you do a lot of riding in loose snow, and even then you may not really want longer since that tends to keep the skis down more. I went from 136 to 144 on my RMK, and I was surprised at how much less it would "wheelie." On the other hand, in loose snow, more track will usually help with acceleration. I mainly went that direction to get stuck less though.
Anyway, putting the track aside, the big things that will help acceleration are gearing down and clutching. The EdgeX and XCSP were geared for top end (looks like 25/40), and you'll definitely gain off the line by gearing down. I'd start by finding the sprockets and chain from a RMK (19/39 and 21/41 were most common), or you could just buy new pieces. The 19/39 is a 28% gear reduction, which should make for a nice kick in the pants. Top speed is around 80 with 19/39 and 9t drivers – plenty fast to my mind, but again, I'm more into the off-trail stuff. If you're thinking of gearing and clutching, I'd say gear down first. A big gear change will affect clutching, assuming it's good to start with. For clutching, either start stock and experiment, or see if anyone still sells a setup that sounds promising. Lastly, if that doesn't give you enough, I'd keep an eye out for a pipe. I've read SLP's pipe was worth some real HP on those. Reeds might also give you a little; lots of guys put "big air" kits on those too. Still, gear and clutch are going to make be the big difference-makers, IMO.
