ha ha! top secret stuff eh Stu! fair enough, mums the word!
on the engine bay coatings, i would agree with whats already been said, most media blasting could be too harsh, unless it is soda, shell, or even ice if you can find someone who does it yet, been big in the states for some years but not too common over here yet.
da is great if you have the air power behind it, they are very very greedy with only a hobby air compressor they are often too much, and will spend more time static than they will sanding,
bit like johnboy and his 33! ha ha!!!!!