Variable length intake runners, it's where it's at.
So jmac, since this is a datsun 1200 site, how about some rough dimensions for primary, secondary pipes. Or recommendations, for a street A12/15 in a 1200 on exhaust dia through out.
Obviously the cam, the intake system, valves, ports etc etc have a large take on it so that was a pretty useless question but say for a standard a15 since many people are running them as a base upgrade on the a12. Or even the usual a15, quite mild street cam (very broad term i know), and 40mm sidedrafts as most people jump straight to them.