Welcome to the forum.

Also, you want to make sure and run an OEM stator.  The aftermarket ones for the 500 are nothing but problems.  I would second the recommendation for the PT pipe.  That pipe came with my Zilla when I bought it back in 2010.  It is a great low-mid pipe and has an OK top end.... perfect for trail riding IMO.

My Zilla is only for the dunes, so I went with a Q v1 pipe next and the bike really woke up and had tremendous overrev (probably near 9k RPMs).  I went with the no bling look, so that pipe was too shiny with the Nickle plating.

Current setup is a built motor with a stock TM38 taper bored by Jerry Hall and Halls HPR#19 pipe.  Good power in low RPM and great power mid-high RPM.

If your trails are wide enough for the Quadzilla, then it should be a good trail bike with the right pipe, once you iron out the kinks.  Make sure to read up on the engine standard reliability modifications.  Doing those will yield a dependable Zilla, unless you start going big power and you will find the next weakest link in the engine... been there and I'm fixing my engine now.

Again, welcome to the forum and there is a lot of information if you search around.

Good luck,
Larry