Racefit "Growler" - Yamaha FZ1. Racefit Growler is now available for Yamaha FZ1. Racefit - Growler is a MotoGP inspired exhaust for Yamaha FZ1. It is made using all titanium construction and a carbon fibre sleeve (Titanium sleve option also is available). The exhaust has a large 2.5 inch bore with a small aspect ratio can – very similar to the Yamaha M1 GP bike. The finish is raw and technical – just like the factory/works item. Obviously through the use of exotic materials and again just like the factory bikes it is incredibly light-weight weighing just 825g (including it’s titanium strap). Naturally with all Racefit exhausts the sound is incredible - it doesn’t just only look like a Moto GP exhaust as it captures the attention of everyone who’s laid eyes upon it and also makes the hair on the back of your neck stand up when it is fired up.