ORIGINAL: csp1971
With the Baja, you'll be stuck with the stock muffler, stock fm radio (kinda good kinda bad).
HPI make an aftermarket muffler for it now. It came out about 2 weeks ago, and comes as standard on the Baja 5B SS.
http://www.hpieurope.com/piw.php?lang=en&partNo=86690
Also, what do you mean I can only use the stock FM radio? I have a Spektrum DX3.0 in both my Savages, and I was almost sure I could use it on a Baja...