...dang...
..well, the 150 isn't "restricted"..per say..
..only the 50cc scoots are actually restricted, due to the speed and insurance laws and such...
..however, if you would like quicker take-off and acceleration through mid-range, you can go .5 gram lighter on your variator rollers without really affecting top speed..
..might even gain a lil there too, if your engine wasn't turning highest rpms at your normal cruising speed...
..if you want to open it up a lil more, then replace your stock airbox with a free-flow filter, such as a K&N..
..however, if you do that mod you will need to increase the size of your carburetor's main jet, to keep your fuel mixture from becoming lean, due to the increased air intake..
..the filter will also give your scoot a louder, more "throaty" sound...
..ummm...
..may the Force be with you, brother...