NS-4 EXH SYS YFZ450R/X SS.AK '09-12

Every DR.D exhaust is built, developed, and tested by Doug Dubach. DR.D pours more time into track testing, with more experience, than any other company. A former Factory Supercross rider and career test rider, Dubach is widely considered ‘the greatest test rider in the sport’. DR.D exhaust performance is unequalled; while others simply search for peak horsepower on a dyno, Dubach spends hours riding stock bikes to understand where each needs improved power character and/or more power! The DR.D R&D Test Center in Warner Springs, California is Dubach’s labor of love; it houses our engineering team, advanced CAD/CAM technologies, Data Acquisition, Dyno Jet 500 and most importantly, three (3) unique test tracks. DR.D exhausts are not mass produced, each exhaust is unique and each has been developed on the track to best improve the bikes power character. You won’t find ‘universal’ components, such as heavy springs and gaskets, in our construction because cutting corners, on the track or in production, is never beneficial.