I hit a metal bar on the freeway yesterday, didn't see it until I ran it over. After a Jan 1, 2005 pickup date, this was the longest I have owned a new car without a single scratch. The streak is now over.
Anyway, there are several scratches, all about 3 inches long, ranging from what look like clearcoat depth to one where the undercoat can be seen, can't tell if it's down to bare metal. They are very narrow, though, like what a knifle blade would do.
I have not heard of gs27 but I assume it is similar to Meguiars scratch X. These types of products will only cover up scratches, not remove them. The only exception might be if it is an extremely light mark, which I would call more of a blemish rather than a scratch. The only way to truley remove it, and again I must emphasize that like others have said if it goes through the clear coat, its too deep, you need the heat of a high speed buffer,or at the least a Dewalt 443 or cyclo. These are differant from the Porter cable in that the motors are much stronger and won't bog down under pressure. The compounds are designed to "level" the walls of the scratch to blend it in making it less noticable. If you need more on this PM me here or my web site, and I will be glad to help further. Gary