Megan Racing Stainless Exhaust VW 20th Anniversary GTI 1.8. This Cat back is only for the 20th Anniversary Edition VW GTI. This Cat Back system is made with 100% T-304 stainless steel with fully polished piping and CNC machined flanges. This improves horsepower and performance with its straight-through design. The piping is 2.5" and comes with everything you need to install.