As has been said by others it is probably a case of your dealer being given an allocation and at this time there is a constraint forcing you to take the Z51 if you want Mag ride which is a really nice option if you use your C8 for much touring. Given that you are not going to be able to drive it until April you may want to consider taking a pass on the current allocation and waiting a few weeks for your dealer's next allocation which may not have the constraint. Personally I would not order a Z51 in the C8 even though I had it on my first C7 and I had 2 Grand Sport C7s. With the C8 I was able to order every option I wanted, and there were lots, without going for the Z51. I especially didn't want the summer only Michelin Pilot Sport 4S tires that come on the Z51. I wanted the Michelin AS tires. They ride better, are quieter on the highway, wear longer and can be driven in the cold weather where the 4S can not. I have also driven the Z51 and the non Z51 back to back and could not tell the difference under normal driving. If you plan to track your car then go for the Z51 but otherwise it is a significant expense for slightly larger brakes.