I have just fitted a Towsure towbar to my Mk3 Astra. One of the silencer mounting bars is rubbing against the vertical part of the bar and making a frightful noise. I have tried grinding a bit of the silencer bar away (the curly thing that the rubber mounting goes on) but it just seems to let the exhaust move further and start rubbing/ knocking again. The exhaust does seem a tad too long as it has also been touching the bumper. I have been trying to break the joint between the middle and tail section of the exhaust so I can telescope it 10mm which would solve the problem. The exhaust sections are in very good condition and not very old but I can't shift them. I have been using loads of WD 40 and chiseling away with old screwdrivers but to no avail.