in Japan they are only 600yen(about $5). They come in different sizes to match your tailpipe diameter. IF you get the right one it is loud as hell & VERY annoying( like the whissle tips, you all remember BubbRubb right). If it is too small, you will very little to no sound at all.
Sounds nothing like a turbo. That pertucular one he is selling looks like it would work on the 2" dia. pipe.
They are actually quite big sellers in Japan. For the girls with their rides though. Not many guys buy them.