I have the following in my car and really haven't noticed any ill effects. I have a Kenwood KAC-X4R and KAC-X1R (bridged at 1 ohm) and I haven't had any issues yet. I ran 4 gauge wiring from the battery to a distrubition block, and 4 gauge into both amps. In all honesty, I didn't buy the car for the gas mileage (though it is a plus) and I plan on dynamating the floor, doors, rear deck lid and trunk. I will be using dynamat extreme. I AM NOT dynamting the the car for sound quality (though it will be a night and day difference) but I want to get rid of the road noise. I commute 25 miles each way (i have hov access) so I would like to have a quieter ride. I don't have a loud system, just clean and accurate. It really makes the commute that much better. I think after it's all said and done, I might have added another 50 pounds to the car.