It has no vacuum assist however, so you'll need to turn it off each time. The results speak for themselves. We took a mildly modified 1996 Evolution from 58hp to 89hp. RPM and the bike feels like a completely different machine. The torque curve has a noticeable dip at 2250 rpm, but the ride from there up is a real joy.
Nothing is free, however.
This kind of major engine modification does have a few minor drawbacks. First of all, you forever loose the calm, predictable beast to which you have grown accustomed. It is now something more along the lines of a funky jazz drummer's beat. A high loping cam will do that. It will also dramatically increase the volume of the exhaust note.