i put the polini on it last week, (waiting for the right intake)- i will say it's a bitch. you have to take out the ports ON THE KIT to match the bottom of the case and you need to weld more material to the case to properly match the non throttle-side transfer port. intake port on the kit is at 17.5, it'll end up with a 16:16sha or 19phbg hopefully by the weekend and i'll be able to report what it does with the pancake.
soon we'll know if it was worth it... and then if a pipe makes the difference. the benelli i took the clutch off of was a 3 shoe (stock). puch clutches fit if i remember correctly.
as far as circuit pipes, i might mock it up to see if i can weld a tab for mounting where the pancake mounts on the clutch cover bolt. also definitely mount up the front of the circuits, or the exhaust nuts rattle off, or flanges bend