Dear All, The knocking you describe is coming almost certainly from the protective (admittedly rather flimsy) tray underneath the engine. It is secured with what look almost like screws, but, in reality, tun out to be a press-stud. If these studs (there are about 10 of them) are in any way loose, the tray looses any structural integrity it might once have had and rattles and vibrates like hell! Mine does it to, although I haven't taken it back to the garage yet, as it is only 400 miles old, but will mention it at the 150o mile check and will let you know what they think. Richard