I have two 10" infinity subs with 350 rms being powered by a kenwood mono amp putting out 500 rms in a 1998 monte carlo ls. The headlights tend to dim, not horribly, but to a noticeable extent. What would be the first step to fixing this. Also, i was told that having a "system" will reduce gas mileage, can anyone shed some light on this? Thank you