This is the HPI Aluminum Tuned Pipe Set and is intended for use with the HPI Baja family of vehicles. This set includes the HD steel header, and is a stock replacement part for the Baja 5SC, but is an excellent upgrade part for the 5B and 5T vehicles. This tuned pipe set delivers improved durability, more power and quicker throttle response than the stock muffler. The header is made from large diameter steel tubing for extra strength. The exhaust flows smoothly from the steel header into an expansion pipe that directs the exhaust cleanly out the back of the chassis, while the stinger design has been optimized for a perfect fit in the Baja rear cage. The sound has been tuned to sound like a 2-stroke motorcycle engine for realistic performance, and is much louder than the stock pipe. This set includes everything needed for installation, just bolt it on and feel the difference!