yeah, that's what i thought. B20a or b18a (not the b18a1) aren't compatible to 'normal' b-series parts. However, that being said, the sleeves on the b20a are supposed to be better than the 'normal' b20, which is normally the b20's weak point. As a result... the answer is... forced induction.
just gonna put some emphasis on the FI. lol