I have actually used 3 different mobos today.... my good old EPIA, an old shuttle I had laying around and a GigaByte MA78GM-S2H and with all three, no luck.
So, I now have used two different PSU's and three different mobo's without luck.
Although I prefer a nice and clean install in the trunk only, I am now looking into mounting the HD unit under the bonnet.
Some BMW E46 types have the battery in the front under the bonnet in a nice, dry and sealed compartment. As mine has the battery in the trunk, this means I have some room left... initial test showed that by placing the directed unit there, the interference is minimal, even with the M2.
As there's already a power connection available in that area, only thing I need to do now is extend mitch's cable with a 8P minidin cable, route the antenna and audio cables and I should be ready...... hopefully...
I will keep you posted... not giving up my hope for radio.. yet..