I can't post a link (guess I don't know enough about laptops yet), but the kit part number is "LXTGZ4" at Tower hobbies. They are out-of-stock at the moment, but I'm sure it's available elsewhere.

And TQRC Racing also sells a body set kit like the HPI one, from Tamiya, but all of them completely outfit a body. You may find just an exhaust tip, so try taking a look at TQRC. I shop with them about once a month, and they are reliable and a bit less expensive than most larger online outlets.