As far as advance goes i'd go mechanical,don't like vacumn.When i bought my first boat it had points in it and it start cutting out at 5000 rpm's.I changed points,rotor,condensor,cap,wires plugs and plugs and still did not run like it should on top end.Changed to msd and problem solved.No problems for 6 years straight.That's my experience anyway.I agree on changing things one at a time so you know what helped and how much.