Works great simple bolt on sound reduction. Installed on 2001 Yamaha YZ426F stock exhaust. On the 426, carb rejetting absolutely required. Was sluggish and unresponsive on the low end before carb tweaks. Runs like a champ now and dB Dawg does a great job of knocking down sound output without any noticeable reduction in power. Because carb tweaks were required on the 426, it needs to be installed and kept on the bike. Not added or removed at will as some might suggest.

Nice... fit very well... i even nice to see... less noise... for the price a very good product