I fitted the BGM Superstrong last year. Although I just have an untuned standard engine I'm very happy with it's smooth operation. And I guess it would cope quite well with much more powerful engines.
Despite the price the S-Box was on my radar as well. But if I interpret the description on their webside right it's more designed for kitted/tuned engines?
What is the best way to check a brand new exhaust for leaks (untidy welding) BEFORE fitting and test riding it? Does simply filling it with water work (without causing any damage)? The exhaust in mind would be a Vespa box-type.
Maybe the 3 plate clutch is a bit stressed with the increased power of your engine? As the genuine Piaggio 4 plate clutches seem to have their issues too maybe you want to think about a BGM one? I fitted one to my (standard) P2 engine and although I didn't do a lot miles so far the feel (and ease of...
Ducksta, do you run your scooter with the engine panel fitted? If so, do you notice any difference on a long(ish) run, when your carb sucks the preheated air? And did the foamfilter ever come loose?