ahhh thats nice to know..... i presume a factory rb20det manifold would flow enough for a 450 or so rwhp rb30det?.... if its just a case of match porting the manifold to suit the head thats easy as pie.... is there any thing else that makes the fitting of the manifold to the head difficult like water galleries etc??? and is it my stupid way of thinking or would this mean that if you wanted to you could use a greddy plenum for a rb25 on a rb20 after porting the head slightly to match the intake manifold??? ,and yeah that helps me stir up thoughts of throwing even more cash at my r32 now YOU BASTARD!!!! haha jk