Cut out's came up in one of the other threads I recently read. I highly recommend QTP electric cut outs. Good solid construction, strong motors, durable housings etc etc. Had them on my 4th gen, worked flawlessly for years. I would say if I drove it 3 or 4 times a week, I cycled the cut out at least twice per ride. When I first put them on I would run with them open almost all the time, and closed them up if I saw a cop. Never had a problem. This will aslo allow you to go with a quieter muffler set up, since you wont have to worry about missing the loud sound when you open them up.
Cats wont do much with "drone", but should definitely clean up that "raspy" sound if you have it. As for brand, I havn't done research for the 5th gen yet, but carsound cats are highly recommended on other applications. Good luck!