I think it would work if you were going for an Outlaw Boxster look on the whole car. Saying that, I'm not really sure what an Outlaw Boxster would look like.
But I think done right, I could get into it. I've seen matte black and carbon fiber wrap on the hood of silver boxsters. Some look good, some not so good.
Mangus Walker has developed a pretty interesting multi-color Outlaw look with his early 911's and I think he's beginning to push into 911SC territory. Look at some of his cars for inspiration.
I'm having my Arctic Silver DE/AutoX Boxster upgraded this winter and it's going to sport a pair of Guards Red mirrors along with red GT3 style side stripes and wheels. Not an Outlaw look, but red definitely adds to a silver car.
Rick