Josh he's on about the intake/fuelling side not the whole engine.
Jaysey : They are a bitch to map, judging from others experiences. Lots involved, either custom made manifold or £££VictorX/Toda/Jenvey and most likely rare. I wouldn't say it is worth the hassle and time and money for what might lose you power (maybe top end gain but mid range slump - depending on spec/mapping).Oh a Honda got it pretty much right as standard 100bhp per litre. Yes B16's can be fettled but if you want an UP in power then B18/B20 swap would be less of a hassle than ITB's in my opinion.
My mates runnin an ek4 vti on a custom bike throttle body setup and its awesome! I drive a 94 eg6 vti and thought mine was fairly rapid till I drove his! The noise when in tec and the increase in torque right across the rev range could really be felt, it now sits with evos/imprezas without to much trouble! The full conversion including a custom made intake manifold, the bodies and mapping cost him around 1500 quid all in! In my opinion well worth it!