ok so i have a 2008 Base model with the monsoon system with XM bur no OnStar. i have noticed at higher volumes i lose the Bass in my speakers. my front door speakers have the seperate driver and tweeter. what can i do to keep the bass at all volumes without having to install a amp and re-wire the entire thing?? i want to put some JL Audio C-650 or Infinity Kappa Perfect 6.1 and possibly put the same in the rear in lieu of the 6 x 9's currently there. I do not want to replace the factory HU at this point, since i like the XM thing and not wanting to buy an external unit. so give me your expertise so i can crank up some god tunes.