Soundracer has been out for a couple years, and while it gets a lot of guff from the performance community, it is actually a fun little toy if you can find one for around $30 or so (Amazon). It works by plugging into your 12-volt power receptacle, and reading the alternator in order to produce a high performance engine soundtrack, then playing sounds over top your existing engine through an FM station on your stereo system.
You can choose between a V8, V10, and Ferrari F12, depending on which module you purchase, and as a bonus, the tuner can be used to play MP3’s through your vehicles FM stereo. The biggest problem with the Soundracer is it does not execute itself well with all vehicles. Some alternators will not give enough information to follow the rpm’s of your engine, but their website gives a list of common problem vehicles.
Check out the video introduction below: