Stock blow-off valve of Evo is equipped with the function that relieves the boost pressure if the boost goes up too much at the time of accelerator-on. Therefore, the boost of Evo is not raised more than fixed boost pressure with stock blow-off. But, on the other hand, it will become the cause of turbine blow if the blow-off valve is removed. As for a TOMEI blow-off valve, only the boost pressure relief function has eliminated while the turbine protection function is left. Moreover, since we applied a bypass type instead of an air release type, there is no worry for engine stall or the deviation of a fuel control. It is an item indispensable to tuning of 4G63 by any means.
*Perfect for anyone looking to upgrade the weak plastic Evo 8 bov or anyone with Evo 9 metal Bov looking to go with high boost!*