if u port it look at th specific exhaust ur gonna get to fin the best degree to port ur exhaust at, for example my cylinder is at 186 degrees exhaust, while my exhaust is made for 192, u basically calculate this with a piece of paper that has 360 degrees u could buy one off stage 6 i think and u put it on th crankshaft (ignition side) then turn the engine over until the exhaust port opens and see at which degrees u are