Just finished installing a Big Gun Utility Quiet Series pipe, Dial-A-Jet and Thunder Product's TPI valve, which is an additional valve in the lid of the air box allowing more air to enter the air box with the option to regulate the amount.
I have the Dial-A-Jet set at the middle range, running the TPI valve halfway open. Spark plug is cardboard brown and the Grizz is running superb!
Taking the carburetor off was much easier than I though. Just a bit time consuming. The whole process took about 4 hours to install everything and tune the engine. Overall I am very pleased with the outcome. The low-end power I lost switching to the 26" Mud Lites was regain with these options. The pipe is a bit louder than the stock pipe, but much better sounding! The throttle response is outstanding with these additions.