The unique attributes of the Dr. Ds step system allow for a more efficient intake stroke. It does this by resisting the reflective exhaust pulse during the intake / exhaust overlap. In plain language, the carefully tuned steps in the system allow for a lower net cylinder pressure, which gives a crisper throttle response from bottom to top. The key advantage of the Step System is improved low end response with substantial gain in the mid and top ranges. Dyno tests show a 3.6 horsepower increase at peak. The Dr. D Spark Arrestor System is designed for riders who are looking for the same extraordinary performance characteristics of the Dr. D Race System, but also need to quickly adapt the system to meet USFS spark arrestor and/or noise level requirements. The DR. D complete exhaust system is birthed from Doug Dubach, who brings years of experience to the motocross and supercross scene. DR. D constructed this complete exhaust system with an aluminum muffler in conjunction with a magnesium end cap to reduce weight and stainless steel head and mid pipe to provide long lasting durability. DR. D welds the stainless steel mid pipe to the aluminum muffler to eliminate weak points and excessive weight in the exhaust system that spring connections can cause. To create a solid mounting point DR. D uses a CNC billet hanger on the extruded aluminum muffler sleeve. The magnesium end cap on the DR. D complete exhaust system is easily removable to access the spark arrestor screen. With the spark arrestor installed the exhaust system meets USFS approval. Repacking the DR. D aluminum muffler is simple with the removable bolts on the lower end of the sleeve. The DR. D complete exhaust system includes: aluminum muffler with stainless steel mid pipe, stainless steel head pipe, USFS-approved spark arrestor.

The T-4 GP System is a tunable version of Pro Circuits more exotic Ti-4R System and includes the all new, sound-reducing RC-4 Resonance Chamber. Pro Circuit developed T-4 GP Complete Exhaust System with the intention of satisfying your motorcycles thirst for more power at a reasonable cost. It will boost your bikes overall power by not only adding raw performance but will also add power by shaving weight. The durability of the T-4 GP is beefed up by using stainless steel for the head and mid pipe. Pro Circuit stepped up the performance of the T-4 GP, making it tunable by including both spark arrestor and race tip so you can choose your end cap to match your riding conditions. Lightweight 6061 T-6 aluminum sleeve. The T-4 GP complete system lowers and centralizes the motorcycles center of gravity for improved handling and performance. Each model is rigorously track and dyno tested to produce maximum performance and usability. A removable U.S.F.S.-approved spark arrestor and race tip are included with every exhaust. Maintenance on the T-4 GP exhaust is simple with the bolt-on removable end cap. RC-4 Resonance Chamber to reduce noise. Billet aluminum mounting bracket. Meets AMA sound requirements. Note: The RC-4 Resonance Chamber, depending on year of your bike, might not be included with the system. The T-4 GP exhaust gives you the ability to take your dirt bike off the track to the unbeaten path with the U.S.F.S.-approved spark arrestor but, when you are on the track using the race tip, the T-4 will meet all AMA and FIM sound restrictions.

The FMF Factory 4.1 slip-on exhaust is the same exhaust that professional racers use to bring home championships around the world. FMF constructed the Factory 4.1 slip-on exhaust to offer the lightest weight slip-on on the market. The technology in this slip-on exhaust cannot be found in any other exhaust. The proprietary Chamber Core technology allows for smoother and more efficient exhaust flow to maximize the power output. Since the Factory 4.1 slip-on exhaust is meant to be used for competition, FMF made this pipe ready to take to the track straight out of the box. The FMF Factory 4.1 has been designed to allow for easy maintenance with a removable sleeve for repacking and it offers the ability to fine tune the performance of the exhaust with the addition of tuning inserts and the option of a spark arrestor to give you no boundaries. The lightest system available. Boosts low-mid torque and offers a broader powerband with more over-rev. Patented Chamber Core for optimum performance. Engineered for compactness and centralized mass for improved handling. Exclusive mounting design. Easily serviced for re-packing. Slip-on mufflers are available with a titanium or stainless steel midpipe. Customizable with performance tuning inserts and spark arrestor module. Meets AMA sound requirements on most models. Detailed Specifications: Type: Slip-On. Configuration: Single. Construction: Titanium. Finish: Blue anodized. Midpipe: Stainless steel. Endcap: Stainless steel. Quiet insert: 94dB insert (included). Weight: 5.2 pounds. Note: For closed course competition use only. Not intended for street use.