Naraku Chrome Racing Performance Exhaust for 50cc 4-Stroke 139QMB Chinese ScootersQMB139 Race Exhaust by Naraku Taiwan. NK400.03 The crossover combines optical NARAKU racing design with an internal structure of the precisely tailored to the physical requirements of a 4-stroke engine. And the road with approval by e-mark. Most 4-stroke exhaust systems are simply borrowed from the manufacturers of the 2-cycle series, and only the brackets have been adjusted. Result is a visually appealing plant with generally worse performance figures than the original exhaust. The crossover allows coordinated by the internal structure of the current upper limit of performance development at GY6 50cc engines with an exhaust system. So It is one of the most powerful systems for these engines. This system comes complete with its chrome and carbon fiber muffler stands out as a visual highlight of the mass. Chrome Edition.**NOTE: DELIVERY MAY TAKE UP TO 2-3 WEEKS****