The XL-pro should have most of the higher grade components so you shouldn't need much upgrading. Maybe look into the front tail drive upgrade (MA0832). It's a sturdier design and will hold up to hard flying. The CNC tail rotor gearbox is a nice solid piece too. I have had trouble keeping my tail rotor gears meshed properly in the plastic gearbox.

Oh, and make sure you use threadlock when you put her back together.

Ben