Ok Guys here is the deal on a base model there is what appears to be a 6x9" opening in the door but it's for a very slim 6x9". The base factory space is on an angle also look at this pic.
You will need to create a spacer and SEAL THE SPEAKER properly from from to back to make sure there arent any air leaks and etc! Air leaks kill the midbass! I'd recommend that you pay a local shop in your area a visit and just talk with them and let them explain this to you in person. Try these guy they do great work.
Adams Mobile Audio & Design
(262) 781-5600
16825 W Lisbon Rd, Brookfield, WI 53005