Hey rebel, so doing the math for a stock AV7 with a dellorto 15.15 carb and a malossi 15mm intake (not port matched) I keep coming up with a starting point of 10.8 or basically 11mm. Now the drilling is where I get a bit confused. I have the two baffled blunderbuss exhaust. So I drill the exit hole where the exit pipe would go when assembled and then drill two extra holes with a 1/8th bit to make more baffling? Or the two baffle holes which I circled in red? Then add a larger piping for the exit?