It doesn't cost anything to keep all your stock parts, so why not? Believe it or not, I even pulled and kept the stock factory oil filter (with the handwritten tech notes on it) right after delivery. Same thing with the stock air filters, exhaust, air tubes, seat rails, tires, etc. One of these days, someone will flip out that all of those original parts are wrapped up, cataloged, and safely stored. You'd be surprised at how fast time flies - my car still looks, smells, and drives like new but it is 12 years old. By the time someone is able to separate me from my car, it will be a valuable classic...
For now, I just love it.