I bought my Dad's LS430. I had a body shop fix all the parking lot dings, and the car still runs great (200,000 miles). I want to put bigger wheels and tires on, put an exhaust system on it. (its registered in Alaska, so I can cut out the cat converter) and maybe add a performance chip, also the rear subwoofer is toast. I would very much appreciate any advice on these topics. Thanks

 

I doubt many people will recommend cutting out the cat even if it’s legal where you live. The gains will be minimal and could lead to other issues if not tuned properly. You’d probably get more power from some good maintenance. These aren’t performance cars, fix the sub, get some wheels, do a muffler delete, and enjoy it for what it is.
If you are determined then there are supercharger kits, although they are $$$$. Or just trade it for a sports car.

 

^^ What Jay said^^

You can re-foam the Sub if it's just the surround that has disintegrated, but if the voice coil is broken then you'll need a new Sub.
I believe there is a company that does a flash for the ECU but the gains are not huge from what I heard.

 

"What Jay said" This is a cruiser,not a racer. Otherwise, maybe what you want is '69 Corvette...