i had a powerflow stainless cat back exhaust to my 165.cost 550 from mr tyre mansfield,was a bit of a panic buy due to mot but well pleased with quality and cheaper than fiat mild steel genuine part
So for my exhaust just been shown under the car. There is a tin plate that sits behind the bumper and above the exhaust which is causing the knocking. They have said they can drop the exhaust or bend the plate up just a touch. Bend the plate it is!