i have a powerflow on mine,i think it`s ok,nice deep tone low down and at idle.it does get louder around 2000rpm !amazed but not enough to do my tits in,when i`m cruising on the motorway and around town it`s perfectly silent, 8) i told them to make sure it wasn`t "boy racer" loud!! however to highlight what craig and slim have said about workmanship,they(drivers in glasgow)fitted the middle silencer too close to the rear axle,i only found this out when the car was MOT`d x) ,when i phoned them up to kick up hell ~ they were actualy ok about it and rectified it.if u do decide to go powerflow g