I had a powerflow fitted once to one of my old VR6s... I asked for a subtle exhaust note and came away with something that was poorly welded and embarassingly loud... so in a word... no! I've also had Hayward & Scott which wasa lovely sounding exhaust but very expensive Does the original system need replacing? If not just change the backbox. I've kept my original exhaust on this time round but when it goes will probably get a jetex