Hi have just bought a ninja ii backbox for my subaru impreza bugeye gx but already have an sti backbox on, they are both 2.5 bore and i believe the gx as standard is 2.25 bore, so what size of gasket would i need if the centre section is 2.25 but the backbox bore is 2.5?

Thanks.

Tommy

 

2.5" gasket

Standard Sti and wrx both have the same back box pipework diameter - 2.25"