I used Acousta-Fil Boa too, in fact theres a photo of me in mid can action in my profile pic (I dont get out much!). My 2005 1.8 K Series has a Powerspeed system which failed a pre test at Castle Coombe last year being over the limit set at 100dbA. I bought several bags from Acousta-Fil and the measured level on the day was 96dbA a pretty good reduction. Easy process to fill and the Boa is not at all abrasive to handle. Pretty easy to take the can off the car too if you are finding it difficult to get the last Allen screw out of the can - you know the one directly facing the side skin which is slightly chewed up.