Hi Harry,
They are called image MC on central coast. Come to think of it the manager there was telling about some guru up there who can work your stock pipes for a better sound.
Can't remember how much but I think was around 300 or 400. I will give him a call and see if I can get the number, much cheaper then cobra or Vance& Hines.
You know there have been a couple of times where cars have not seen me but with a quick rev have heard me and made them pull back in. You just cant here the stock pipes at all.