I own an 03 Hustler z with a 23 hp kawasaki engine. It currently has about 1100 hrs on it and still runs great. My question is... When it comes time to rebuild the engine, is it possible to convert it to 25hp? I know that the displacement of the 23 and the 25 are the same...is it differences in the head assembly and carb that make more hp? Any info would be appreciated.