i know piaggio engines are far superior to peugeots, and my mate flying past my speedfight on his sr50 backs this up. but what makes them more powerfull, is it the port timings or something?
peugeot engines are a very crap design, the cranks are crap and shake themselves to bits, the cases are also a crap design for flow and theres hardly any real juicy tuning goodies for them...
Piaggio make the best scooter engine because they are one of the oldest scooter manufactures going, they've perfected their designs over the years. Their 50cc "Hi-per pro" 2T engines are designed to be high performance not just an ordinary A to B engine found in most other scooters. They have bigger carbs as standard than most other scoots too.
im badly regretting buying a pug now, especialy as my mates sr50 only has a pipe and malossi variator but leaves my bike which has more goodies on than his in the dust
if you think your 50 is slow for a 50, not so much as the speedfight 100 is, for a 100cc scooter. also for the zip, Polini make a 70cc engine that knocks out 25bhp....... for a price.