Are there any after market 6 x 9 that will fit the rear deck of a 2001 coupe ex with minimal alterations? What is the maximum depth they can be? Thanks in advance for any help

 

most 6x9's will fit - the mounting holes are standard. you have some magnet size issues with the torsion bars, but no real depth issue since you have the whole trunk. The torsion bar clearance can be easily measured inside your trunk. you can see the back of the speaker from the trunk, just measure down from the rear deck to the torsion bar.

while you are in the trunk you can look for the screws that hold the rear speaker grill covers on. they will be brass in color and visible through holes in the rear deck metal. the covers screw onto the rear deck panel, so you have to look up inside the rear deck space to see them.

make sure you use some weatherstripping foam around the new 6x9 to maintain a seal against the factory grill. if not, your bass response will greatly suffer.

my build log (link in sig) can give you other ideas for the car (sedan but a lot is similar)