Most of the testing has shown little or un-noticeable compressor damage when done correctly. There have been people reporting damage, but it has only been a couple and I think one on this forum said they were not running an air filter and had sucked some dust and dirt into the turbo as well.

I can't say 100% that nothing will happen to your turbo. If done right, my opinion is any affects would be very minimal if anything at all, but I want to be as honest as possible with the members of the forum.

Rice Racing on this forum has done a great deal of testing with pre-turbo injection. You could ask him about the method he uses.