I've worked on a couple cars with the Z7 kit. Overall it seemed nice. Both sent the pipes to JetHot for coating etc.

From a mechanical standpoint, the Z7 wasn't easy to work around. It had to be unbolted and moved to pull a transmission. The pipes also gets very close to the rear valve cover. Meaning if you need to do anything under there, you have to disassemble as well. But then we have to drain coolant in most years to pull the rear cover.