RE: Hop ups
I would go with the aluminum steering upgrades.. you can buy them off ebay .. I think it's 15 bucks for the set without bearings or 50 bucks for teh setup with bearings. I bought the 15 dollar version and went and picked up two 99 cent bearings and put it in..
upgrade the engine to an OS .18.. that's a cool upgrade!!!
I haven't seen much else that looked like I needed it...