Fuck that, whether you knew it or not you sold him BUM equipment when it came to the exhaust cam. Not that it matters, it's the intake cam that makes all the difference. I would send him back 50 bucks in good faith since you do see GSR and SI cams going for about a 100 bucks a pair. Ask for the cam back though, since he probably does not need it if he is upgrading a GSR.