https://www.youtube.com/watch?v=dFkPdfDZVRQ... I was bother about the hissing on the videos on youtube... but from what I've read most hfc and tp will make the hissing more pronounced... apparently most aftermarket cbe will cause it... but I got use to it after the install... only does it at low rpm deceleration... the benefits (power and sound) outweighs the negative hissing... i'll post my dyno once I get it tuned... I don't have stock dyno's to compare it with...