I've documented steps I've taken to repair the blown subwoofer on 2006 Lexus GS300, but similar steps apply to most subwoofer repairs. The 10" Mark Levinson replacement subwoofer cost well over $500, so it made a perfect sense to spend about $18 on a repair.
Here are previous videos that show how to remove the back seats, rear deck, and the subwoofer for this vehicle. Similar steps apply to many Lexus and Toyota cars.
Here is the after market foam repair kit that perfectly matches the 10" Mark Levinson subwoofer:
This was my first time repairing a speaker, and I must say, some steps were bit tedious, but overall, there weren't any challenging steps, and any motivated individual should be able to do this.
If you fix your subwoofer or have any questions, please let me know in the comments below. Good luck guys.