TPIS Aqua-Lung Throttle Body for Mercury Racing HP525 Engines - Is your stock HP525 throttle body holding you back?  Your big cube Big Block needs one of these! An industry first, these units are designed for engines making over 620 HP, this throttle body has a massive 5" inch X 3.25" inch opening.  Bolts onto HP525 intake manifolds, and features an integral flange for mounting a flame arrestor or air filter of your choice.  * We can modify your HP500 or early HP525 to accept this throttle body. Call for details