When designing the PowerCore 4, FMF looked at their top of the line products to deliver race-inspired performance at an economical price. The end result is a quality muffler with improved torque, increased horsepower and rugged durability all at a price that wont break the bank. Overall increase in power and torque. Durable stainless steel and aluminum construction. Space Age internal packing material for maximum longevity. Hi-Flo modular end cap. Internal shape of core uses Hi-Flo technology. Enhanced sonic evacuation provides for higher flow and increased power. Includes removable spark arrestor. Note: For closed course competition use only. NOT intended for street use. Detailed Specifications: Type: Slip-On. Configuration: Single. Construction: Aluminum. Finish: Champagne anodized. Midpipe: Stainless steel. Endcap: Stainless steel. Spark arrestor: Screen insert (included). Quiet insert: Quiet insert (sold separately). Weight: 5.3 pounds. Note: For closed course competition use only. Not intended for street use.
"Easily installed on 2007 WR450F with stock head pipe & all the usual GYTR mods. Noticeably improved bottom end power. Grunts and pulls much harder down low in the RPM range even in deep sand. Can pull a gear higher in most situations and is harder to stall in corners. Very pleasant deep exhaust sound, but is quite loud. If you ride in areas where "noise" is a problem, then this product won't work for you."