It looks like you've done a pretty good amount already. It really all depends on how much discomfort you're willing to put up with and how much money you're willing to spend.
Here are a few things off the top of my head, some cheap, some not:
-Wheels should be good for quite a bit of weight if you were to go with some sort of light weight racing wheels. I know the Weld Draglites I had on my previous car were a good amount lighter than the stock pony wheels.
-Replace the hood with a fiberglass (or carbon fiber) one. Not sure if they're available for the '05+ cars yet, but you could also look into a fiberglass decklid. It'll probably rattle like ****, but even the decklid is weighs a good amount.
-Remove all of the sound insulation under the carpet, behind the door panels, in the trunk, etc
-Replace the stock front seats. Again it'll drastically change the look of the interior but those seats (especially the leather ones) weigh alot. There are alot of alternatives out there from seats that still look decent but weigh less, to all out fiberglass racing buckets.
-Remove the carpets, interior panels. It'll make the interior ugly as sin and the car will sound like a tin can inside, but those things weigh a ton.
I've personally known guys with fox body cars who have literally gutted everything from the car to the point where the cars were just shells with a dash and two racing buckets. It really all depends on how crazy you want to get.