This is another high quality scooter upgrade part worth considering; a rust resistant stainless steel exhaust kit for 125cc & 150cc GY6 gas scooters. This kit has an oval shaped muffler.
Exhaust Out take mounting hole Distance, Center to Center: 2 Inches
Exhaust Out take Diameter: 1.12 Inches
Muffler Case Length: 12 Inches
Muffler Exhaust Diameter: 2.25 Inches