The z400 seat is so the couch and very comfortable. The KFX450 seat is alot like the yfz seat except I don't feel the seat pan as much. I like the gripper seat cover but will be switching to aftermarket soon. Probably a Quadtech hump seat if it adds foam. They are a little expensive but I want comfort for the long haul.
As far as the engine covers I think you could paint them with engine paint any color you want. The stock color wears off so fast ( mine are down to metal) and I know Lolli will build an awesome quad anyway....