This kit is compatible with Mach 460 systems, despite the difference in impedance. The only minor issue is that these speakers with 8ohm impedance on a 4ohm system will have slightly less peak volume output (we're talking like 3db, which is not really noticeable to human ears, especially at higher volumes). In exchange, you get better range and less distortion at higher volumes (though that's not all due to the impedance difference).