This question has been bugging me for a little bit now. When thrusters were first introduced and unless I am mistaken, they were designed as twin fins with more thrust. Nowadays I think they’ve evolved into a unison of three fins. I think the two are completely different concepts. I also think that the thruster was designed for wider tail surfboards of about 15" plus. I’m going to throw Greg Griffins “super thruster” into the mix and speculate it only exists on tails of this width. I’m also guessing that any narrower and the quads would conflict with the single fin? I’m also going to throw my two cents worth in and say that on narrow tails a thruster should be treated as a single fin with large sidebites. See the difference?