Not as much as you think...the Type-II headers are only marginally bigger. Type-II head is what received a lot of work to increase the cars horsepower to 230.
It would be more worth it in the long run to get custom headers from either Legendary94GS (Jeff) or DV8 (Christian). You would still pay the same amount of labor for pulling the engine out...wouldn't you rather put in headers that would be worth dropping in? I certainly would.