Basically right now you have a B18B LS head on the motor. You can covert the engine to VTEC (there is some machining involved and you need to drill, tap and plumb an oil feed line) with any of the VTEC heads. The B18C1 head is a little different and has a smaller combustion chamber (resulting in higher compression with the same pistons) and is debateable but probably one of the most efficent heads. The head of an ITR is just a modified (some porting and a valve job) B16A head. Honda doens't really make a crap head (except the 8-valve Civic CX head I used to have) so any of them are desireable. You don't really need VTEC if your going turbo however. The added lift and duration of a set of VTEC cams is what it is and will make more hp then a non-VTEC but the extra overlap on a VTEC cam isn't as productive on a turbo engine as it is on an NA setup. Long story short, I'd personally rather spend the money on upgrading the bottom end of the engine to withstand more boost (with a turbo, more power is just a crank of the boost controller away if your engine can handle it) than upgrading the head.