For the love of God people!!!!!!!!!
Here's the deal and quit listening to the people that think your VIN blew up the twin towers.
The VIN is a many digit number that among other things, lets the dealer know your build date. This is important because (for example) the brake pads on the 2004 WRX changed mid year. With the VIN, you will get the right brake pads. If you just walk in there with a part number you scoured off the internet (reason #1 why I no longer put part # in my FAQs), you will likely be sitting with your car on jackstands all weekend because you have the wrong part.
The VIN is also computer and/or shop required to look up ANY parts? Why? This is due to the reason above. It assures 100% that any parts given are suitable for your vehicle.
The only killer is when you do odd stuff, like say the H6 upgrade to the rear brakes. This changes your brake pads from 04 WRX to 02/03 Outback. This can and does cause some confusion with dealers. You can handle this by copying a random VIN off of eBay or using a reputable Subaru NASIOC vendor like Subie Gal, Annapolis Subaru, etc.
If you'd like to copy a random VIN off of ebay and wear your tin foil hat into the dealer, you could receive the wrong part. Will you then come here and complain?
VINs are NOT recorded at the dealership when you buy parts. Do you get that tin foil hat wearers? They have zero impact with regard to warranty work.
My VIN is JF1GG29694G803308
Feel free to post this on every internet site ever.