01-03 HONDA XR100: FMF Powercore 4 Complete Exhaust With Stainless Hi-Flo Header - Race (Aluminum) The Mini Powercore 4 is the best bang-for-your-buck performance bolt-on for your mini. Offered as a standard Mini Powercore 4, Closed Course Big Bore System or as a Spark Arrestor Version, the Mini Powercore 4 features a Hi-Flo stainless steel core and formed end caps, an aircraft-grade aluminum canister and a durable stainless steel header It's pounds lighter than stock and you will swear the motor has been bored and stroked with the first twist of the throttle. Hi-Flo core and end cap. Pounds lighter than stock.