I recently upgraded my stock speakers with Sonys. I used 4" up front , no cutting at all,except the speaker connections and the stock covers fit right over. In the rear I used 5.25" and had to enlarge the mounting notches very slightly (easy with a pair of sidecutters). I couldn't use the stock grilles but it looks ok. Then I needed more base so I added a pair of 10" Rockford subs in a box in the trunk ,removed the medkit, made a wooden cover with 2-4" holes and used the grilles from the front speakers. Great sound for cheap!
