Haven't seen anything on these test pipes.
Pros: Pretty solid build, looked real nice out of the box. Has secondary O2 bungs which is nice, although inconveniently placed (more on that later) and even places to bolt the oem brace back on (mine is still off). The fit was perfect, all the bolts were there. Having Z1's 3 hole gasket was nice too.
Warning though, the bolts are bigger than I expected, bigger than stock, I think. I used 16mm sockets for the new bolts, and the nuts were bigger (didn't have the right size so I used a 15mm open-end wrench to try and hold the nuts). Didn't even know nuts are bigger than their respective bolts, this confused me, but it was the same for my FI exhaust hardware too
Sound was nice. I put these in before the exhaust, it added a bit of sound, but surprisingly no drone or rasp paired with the stock exhaust. No smell either, wasn't expecting that.
Con: The only real con was bolts attached to the manifold. If anyone has done the cats themselves, you know some of those bolts are hard to reach, but for one bolt in particular, the second O2 bung was just enough in the way that I couldn't get a socket on the nut to tighten it. And there was no room for a wrench really. That particular place actually had an old stud that I couldn't remove off the manifold, so the bolt went through the pipes and I reused an old nut (I reused a lot of old hardware actually). So basically, one of the nuts holding the pipes is hand tightened plus a ~1/4 turn using a wrench. Yikes. No problems yet, surprisingly, I was expecting serious leak issues, but nothing.
Z1 should really fix this design issue.
Otherwise, great pipes, I would invest in them. Once I put my exhaust, no resonators, 2.5in piping, the car screams. But it's such a low refined rumble, amazing. No super noticeable increase in acceleration, I thought i felt better throttle response, probably not. No tune or dyno or anything yet.
There is drone, obviously, but it's not raspy, just a deep hum that my siblings hated. I'd say go for these, add a nice unresonated exhaust. You won't regret this sound. None of that high-pitched fake stuff.