Austin Racing Motogp style exhaust with Aprilia RSV4.
The exhaust is something different and the build quality is great. The very competitive price is an added bonus and Rich is excellent to deal with.
This video is filmed with the baffle out just to see what it was like as I run the bike on the road with it fitted. The sound is incredible and this video does not do it justice. The first 80 seconds are with the bike in neutral then you can hear the note change when the bike is put in to gear which opens a valve.
More:
http://www.austinracing.info/