Gio Monster GY6 Performance Exhaust Review

[Weldangrind]

I bought a GY6 performance exhaust from www.giobikes.com and I would like to share the installation process.

First is a comparison between the new head pipe and the stock pipe. The new pipe was actually smaller, measuring 18mm (less that 3/4") in diameter. The stock pipe was 22mm (7/8"). Out came the die grinder to cure that.

The flange end where the pipe meets the muffler needed some minor cleanup as well. I ground the rough edges off and ported the inside to remove some welding bulge.

The stock mount location won't work with the new muffler, but you can use the rack mount with a longer bolt.

The new muffler has a perforated plate in the end that acts as a baffle. There are 15 holes in the plate that are 5/32" in diameter. The total surface area of all the holes equals 0.2876", whereas the head pipe area is 0.601". The perforations do create a restriction. I might do the calculations and drill them out later.

Overall, I'm pleased with the design of the new muffler. It essentially has a straight pipe with perforations inside that are wrapped in packing. Once the packing degrades, I can drill out the rivets and use new four stroke packing. Both gasket surfaces required some filing to ensure flatness, but not alot. The sound of the new pipe is noticeably more aggressive without being annoying.