I don't really see how the port timing would be any different with a bigger bore, but you can definitly go wider on the exhaust port with a larger bore. banshee370, care to explain how the timing would be effected by a bigger bore? I probably just don't know enough about big bore sleeves to really know how they effect port timing. also, it is my understanding that if you had +4mm rods and you are running a piston where the wristpin is located 4mm lower than a regular banshee piston, the port timing would be the same as it would be with a stock rod and piston combo. I am no expert in this field either though, but I thought I'd throw in my two pennies.