A stock People 150 is a very quiet bike...something is amiss. First, while the motor is cold, start at the tip of tailpipe, move on to the muffler and then to the headpipe and just wiggle things around, touch all the fastener hardware, to see if you can find anything loose. While you're at it, look around the tailpipe to see if any power mad previous owner has drilled a few extra holes in the muffler back there. Next get a skinny screwdriver and tape a little flag of toilet paper to the the tip. Start up the bike and let it idle and then start probing for leaks. Try to check the entire length of the exhaust system...the tp flag will flutter if it detects escaping exhaust. Hope you find the leak and get things to quiet down.