Okay, so actually he joins MARS/Iron Grenadiers.

Damn. I need me this. An exclusive GI Joe figure of "Iron Grenadiers Trainer" code-named: "Rowdy Roddy Piper".

http://www.mastercollector.com/neat/gijoe/...iperpreview.cfm

I suppose it's appropriate that Piper is part of the heel faction.