I am preparing to purchase the Z1 CSC delete. It is fairly new to the market (this year). The ZSpeed HD CSC was really the only option before, which is why it seems to be the go to solution when you search the forum. A forum member has had the delete kit on his track car for months (pretty sure he was a test car for Z1). He has nothing bad to say about the kit. I'm sure Z1 did their R&D