IMO there is no point in a bigger TB unless your going to raise compression of your engine.. my advice would be, try velocity stacking the cold air feed to your airbox. blox sell them.. or try a mugen or tegiwa airbox, they come with a stack. The engine can only draw in so much volume of air due to compression and piston size and fuel. speeding up the right amount of air is what you want.. adding a bigger volume of air ie larger TB would mean mapping your ecu to compensate for the larger volume. hope this helps