ok, well i have taken the bumper off, it was very easy takes about 30 - 45 mins at the most providing you have tools, all that is behind the bumper is a molded polystrene block (think they call this the 5mph bumper)
i have marked up the bumper, this is the most time consuming (2hrs +) as there isnt really a datum edge to measure from, just lots of multiple measurments to make sure the sensors are in line.
The other problem is that there isnt a truly flat surface to mount the sensors on( except for the bottom,but thats too low and at the wrong angle for the sensors). As such its a comprimise, mine will be about 7 cm from the lip on the bumper ( where it bulges out below the boot lid, if u know what i mean?)
I now need to get a decent hole saw, a spade bit just rips the plastic apart, i practised on a piece of flat guttering, good thing!!!:o
I got my sensors whilst i was in Holland, but if u do a search on yahoo there r lots of companies in the UK offering the kits, mine is made by QUANAN and has 5 sensors and a digital display giving u the distance, the kit got the best buy award from auto express in march '01, you can get the kit with 6 sensors as well, mine are the flush type though the surround does protude a little.
when i looked at the lexus ones they only offered 2 sensors and they were horrible black ones that stuck on to the outside of the bumper about £500 then.
I am planning fitting 3 at the back and 2 at the front. I will try and borrow a digi camera tomo so i can geta few pics for you.
any Q's let me know.
robbie.