Dirtymonkey:
I would suggest to you to go ahead and lift the head and inspect the piston. check to see if you still have the OEM piston. Being an 01 I bet it does and it needs to be replaced with a Wiseco. The 220 OEM pistons have a history of failing and causing alot of heartache and missery.
Go to the top and click on the search function and perform a search on pistons or grenade. Thats right the 220 OEM piston is commonly refered to as a grenade.
The OEM piston will have an alpha designation (A,B,C or D) stamped on top of it that will correspond to the alpha designation stamped to the top of the cylinder.
Good luck.