The problem with sandblasting on a finished car is that the sand goes everywhere. I don't like sandblasting unless it's a bare shell. I always hand sand engine compartments and it's a time consuming job, that's probably why the production shops don't want to touch it. The other thing is contamination. I wipe the engine compartment down about 3 times with wax and grease remover before I start sanding then another 2 times after it's sanded, there's a lot of time involved.
