I have a couple of Zmods that I've raced against miniZ but the miniZ will always out handle the Xmod.
Putting in a miniZ board and use miniZ tires is the best things you can do to the Xmod. Unfortunately weight is the Xmod's biggest problem.
Here is one of my Xmod track cars:
http://www.xmodsource.com/forum/showthread.php?t=15720