I found a custom sub box to fit really nicely in the trunk of my car BUT with the mach 460 that i have the rear speaker hold that is ginormous would have to be taken out. Is there another way to have the speakers mounted in the back with out the huge holder for them. I really want the custom sub box because i will have so much more room in my trunk!

 

you could just remove the 5x7s completely, with the mach 460 system, all the 5x7s in the car are bass speakers and have the component 3 inch mid range speakers, or you could remove the stock 5x7s and get them mounted into their own individual small boxes and put wherever you have room