i am going to fit a 172 kit to my 1.4,i know the rear bumper is a straight swap but wanted to ask about the arch liners,mine has no screws on the rear arch liners it just looks to be clipped behind the arch but the 172 has two screws,which liners should i used when i put the bumper on my car? they are both mk2 ph2 the 172 is a 51 reg and mine is a 55 reg if that helps, thanks