X-Cars are usually King on those kinds of tracks -- they bounce around less thus handle the bumps better at speed.
To weigh the car, make three little stands which are the same height as the scale -- little wood blocks do nicely. Then, one wheel on the scale and the others on the blocks gives you a treasure trove of info. We suggest even weight side-to-side and 35% - 65% front-to-back. Look at the U.S. set-up sheets posted on our site for info on total weight and placement.
http://www.xfactoryrc.com/rc/Tech/SetupSheets.php#2wd
Car looks good.