You still need to gear it...the X-T stock spur won't do anything but kill your clutch fast....
i put the larger tires and rims on the buggy just to check it out. when i ran it i couldn't get any power no matter how i tuned it. then i put the bugy tires back on and retuned and the XTRM was back to a rocket.
i have been searching all over the place to see what i could get to fit. the best options i have found are the 2 speed kit for the xterminator, the 2 speed for the XLB/Mammoth (not sure if they are the same or geared a little different), the OFNA Dominator solid drive or slipper set up, or buying the DADDERS diff adaptor (and just doing it right).
i really didn't want to get into the chopping of the chasis but it doesn't look like i'm gonna have a choice. in order to get the larger spur gear from anything to fit i think i'm gonna have to make some modifacations. there's gonna be some grinding in the spur area and in the flywheel area to get my starter to reach it. and i do believe, like Binary had to do in his XTRM conversion, i am gonna have to set the engine over a little.
all in a days work..[8D]