Decades of racing development went into the design of the FMF Powercore 4 complete exhaust to improve the power and performance of your dirt bike or ATV at a practical price. The FMF Powercore 4 exhaust is a muffler that will boost power and torque throughout the power range, making the Powercore 4 exhaust usable for all types of riding. FMF designed a Hi-Flo end cap and core for the Powercore 4 exhaust system to increase power by creating a free flowing end cap and a core that allows room for exhaust pulse. This results in a consistent power curve. The FMF Powercore 4 exhaust system uses and advanced cross-weave packing that is more durable then the traditional packing. The cross-weave packing also keeps the Powercore 4 at a reasonable sound level by dissipating the exhaust sound. FMF constructed the Powercore 4 muffler using aluminum to keep the weight down with a stainless steel head pipe and components for extended exhaust system durability.
"I got it for my 2007 Yamaha TTR-125L and it made a huge differance. I got more power from low to mid, its much louder and sounds great, and im also really glad that i bought it when i did -i little over 2 months ago- because it was a lot cheaper, i only paided $145, when now the cheapest on here is $161-$179, for the 07' TTR-125. but still i would recommend this to any of my friends. It is definitely the first thing i would recommend doing to any TTR-125."