Goodies arrived today. Time to test fit for the tunnel.
Edit: The initial test fit was eye opening. The seat bases sit wider than stock but I didn't think they would be this wide. No big deal, just have to change the tunnel around a bit. It won't be as obtrusive into the cabin now that's for sure.
And now for the dessert. I've got about 7 inches of head clearance with the seat on the floor. Assuming I halve that I'll still have plenty of room with and without a helmet.