Is the vibration something that affects some but not all Spyders? I'm at nearly 500 miles on my new Spyder and have been driving 70+ all over town, plus a lot of city streets. Probably at least 40-50% of my riding has been on freeways where I would expect to encounter vibrations -- but I don't. I can obviously tell the motor is running but otherwise I have never noticed ANY vibration at all. The ride seems exceptionally smooth, in fact. Since I've been reading this forum I've actually been looking for vibrations like others are experiencing and I'm just not feeling it. At 70-80, my mirrors are perfectly clear, and my wife who is totally sensitive to such things hasn't felt anything in the back seat, either. I thought maybe it was something that would crop up later once the Spyder was better broken in, but now I see that the OP is experiencing it with fewer miles than I've ridden, so it's not a break-in issue. I figure either it must only afflict certain Spyders and I got lucky, or else I'm just totally insensitive to the issue. Maybe because I came to the Spyder from a motorcycle and I'm so used to vibrations from that bike that the **comparative** lack of vibrations in the Spyder makes me think there are none?
For those with the vibration problem, I wonder also whether vibrations might actually be caused by tires just slightly out of balance. Sometimes tires aren't completely balanced internally and that can cause minor vibrations in a car. Maybe the same on a Spyder, and if that was the case, it would be much more noticeable at high speed. It might also explain why the OP has vibrations with a new Spyder and I don't. I suggest he have the tire balance checked before doing anything else.