Powerful Quiet Scoot Design Ideas?

[BeachScoot]

Hi...I am trying to build a more powerful & quiet scoot for city low end mid range and need some help in some mod add on to achieve this.
I have a GY6 157QMJ like VIP Scoot. I am thinking bigger bore kit with a stock muffler, or is there a high flow muffler that is more quiet than others? I have a racing straight thru type that is just too loud and ended plugging a baffle in the end of it for a little relief
Thanks for your ideas

[kz1000st]

Quiet and high flow are a contradiction in terms. Years ago Cycle magazine did a dyno test of various aftermarket exhaust systems. The very best one gave five more horse than stock but was deafening. They recommended the stock exhaust for the best results over all the others.

[HarryGNuts]

You can make your own custom exhaust/muffler and make it as quiet and free flowing as you want. You need to make a big enough blast chamber at the entrance to catch the initial pressure without creating back pressure and use flow through baffles spaced to catch the pulse of the exhaust. If you do the proper math you should be able to make the pulse create a scavenge effect within a certain rpm range to be determined.

I started making my custom high flow low noise exhaust for my gy6 this weekend. My muffler design should give a deep smooth tone, scavenging around 5-7000rpm I should have it all welded up and mounted in a few weeks.

[BeachScoot]

Do post a pic!

I am running a new stock muffler which sounds nice!, the stock air box has low end throttle running nice. Up 1 jet size #110 main jet / #38 pilot, Needle clip higher 1 (leaner), performance CDI, Coil, Valves adjusted, Tuned at sea level. Its running very good idle and low end and strong midrange power revving out well. Next I am looking at a higher profile rear tire as mine are worn:scoot:
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Update just moved the carb needle's clip higher one more (now 2 clicks above center) running BEST YET!!! at sea level, with the 110 main jet/38pilot.
NCY Tranny kit, Now swapped the black 1000lb to 1500lb yellow clutch spring, making it rev a bit better to midrange than the 1000lb one, upper mid range starts getting taller gear with 13.5 Dr Pulley Sliders. The gearing is PERFECT for flat roads 200lbs rider. It has the power to ride out the 13.5 sliders. I did install the 11g Dr Pulley sliders way too revvy (prob good for hills)...so I went back to all 13.5g slider