Well, I sold my Towing Twins and went bigger (64/13/71SS over S480 with race cover). Nothing at all wrong with the Towing Twins, just needed more air considering I'm running a 13mm pump from II. But I did want to say this about that... the II Towing Twins took me 6 or 7 hours to install, even with the small clearance issue with the top turbo and exhaust manifold. Compared to what I'm doing now, II's twins were a piece of cake. They're well-designed. And the turbos are, as always, awesome.