If you not keen on hacking holes into you door cards, sell those speakers and get some JBL GTO components like mine, i just used the plastic surround that comes with em to mount the grill to give it that little extra clearance and used some silicone around the outer edge to avoid any virbration caused by mounting to a metal door.
These are real giant killers, try these with a Metalica Cd it will blow your mind, Ive had the same pair in my Renault 19, And Beemer and there are bullet proof but they dont need a massive amp to kill you.
http://caraudiosecurity.com/shop/product/products_id/4891.html
The only down side in Motorworld selling them for pennies has really hurt the street cred.