i guess you dont know these things unless you hear it from someone else, i really like the strut bar and wanted to keep it, the cats did slightly change colour after being fitted dues to the heat of the exhaust i guess but definetly didnt show signs of rust, also didnt have any rattleing from them..just your luck i suppose
one thing to bear in mind is to make sure you get your mechanic to be carful with the sensors
Paul