Hi, Does anyone know the actual OD of the heater matrix pipes? Everywhere I have seen say 3/4 inch piping will do it however I got a pair of calipers in there and it looks more like 1 inch (25.3 mm) although it is pretty awkward to get calipers in there so I could be wrong. Does anybody know actual size? A4 b6 2.0 auto. TIA!