I have an extra Irwin pipe that has been black powdercoated with Hopper muffler. Also Hopper header that bolts up to the OS. We ran stock and mod with just a 2 bolt change between heats. Pipe won't increase top end much but will accelerate better and cut over a second off our lap times. This pipe got us a US-1 in mod20 two years ago at the Internats with an OS. Pipe header muffler and coupler ready to bolt on $100 shipped USA.