To the BEST OF MY KNOWLEDGE the only way to increase power is to lower back pressure , thatmeans MORE noise! That's on racing motorcycles. I assume that it works the same but I'm no expert on scooters.
![Shrug](images/smilies/shrug2.gif)
![Hmm](images/smilies/smiley_emoticons_confused.gif)
Irish
![Scootin'](images/smilies/emoticon_scooter_2.gif)
P.S. I used to run straight pipes (with engine tuned to them) at the drag strip but there's NO noise police there!