First off the system, Pioneer Deh-7500, Cdt components running off a Kenwood Kac 8401 and two rf he2 12s running off an old pioneer, power (4awg into a dist block to 2 8awg) and signals are run on opposite sides of the car (btw its a 97 maxima). Ive tried regrounding in several spots, ground loop isolator on the rcas, upgraded the rcas, power line filter on both the kenwood amp and the headunit, and basically everything else i could think of. I have not yet done the big 3 but am looking into it. My problem is that i have your classic engine noise- follows pace with rpm, real annoying etc. What i was wondering is what do i do from here will the "big 3" help? what about a new battery? new spark plugs or an alternator? Im not really trying to break the bank here but i have what i feel to be a very nice system for my tastes which i would like to listen to while i drive. Anyhelp would be greatly appreciated.