Unless you are running in competition I wouldn't waste my money however if you want it, get it, but will make no difference in the performance for the way we ride. I have the crane vacuum advance and it works fair but no big difference. I have been racing so long I forgot about how important gas mileage is so I put small springs in my disturber so it would be at total advance at 1200 RPM. Mistake for gas mileage so I recently went to the gray and silver springs that come with the crane kit and looks like my mileage is doing better.
Joe R. is using this set up and it works for him too.
Jack you will need to reset you timing again for sure. It will be a little later than it was with the new Crane vacuum pot.
I'm thinking about installing a MSD ignition on my 2000 ZZ4 to get a little better performance . The kit is sold by Summit #MSD-8501 and consist of a coil , module , rotor and cap for $137.95 and they claim 50% higher coil drive currents than the stock ignition. Has anyone had any experience with this kit. Also if I were to install this kit is it still a good idea to install the Crane adjustable vacuum advance kit also sold by Summit # CRN-99600-1 ?
By the way
The NAPA vacuum advance comes in with a lower vacuum of 10" vs the 15" required with the Crain one. I am not running a long cam (minme is a H.O.T.) so I don't need the lower vacuum that NAPA has.