sorry the top hat dont have the butterfly in it ,that the bit underneath it,the throttle body as you just mentioned..the top hat really just makes the air flow round the bend from boost pipe the throttle body smooth and the one you probly looked at is larger in diameter..... ,the top hat replaces the original metal black piece... the boost pipe replaces the rubber one,, which can as they state suck in and collapse when driving.it is a common thing and there has been many posts on other forums about this rubber pipe collapsing on the z20let engines..,