Well, FWIW I fitted a set of flush fitting parking sensors today. Bit of a mission to get the bumper off but I reckon I could do it in under 10 mins now I know where all the fixings are ! Fitted sensors in same location as factory option sensors, these flush fits look really good.
Once the bumper was off, I unclipped the integral plastic frame and removed the hard polystyrene packing to get good access . One thing I found was tha the inside of the bumper is smooth and would suit an electromagnetic aerial sensor system nicely.
Had to cut slots out of the polystyrene packing to accommodate the sensors, but easy with a hot knife. Bumper was Reasonably easy to re-fit with help of a second pair of hands to offer the bumper up and engage the side slide fittings. Good thing was no need to remove any internal trunk trim (other than the rear light access panels) or jack the car up. Rear light units have to be removed but dead simple with 3 x 10mm nuts each. Spliced into the reverse light and ground wires close to the rear lamp cluster plug. Control ECU and buzzer fitted in the cavity behind the light.
Mick
'06 Aero Blue Coupe