I read those threads and was also wondering on quality because they are so inexpensive. I wonder if the steel used is cheaper "Chinese" 304 and might breakdown fast....Honestly I hope not because they seem like a good alternative to others.
One of those threads posted above was my early review. A while later i can say they are probably ok, but mine developed a pinhole leak on a weld. Makes for an annoying tick. I really need to get it fixed up here soon. Otherwise i still say the fit is good and the HP gains were solid, just my only issue is the small leak.
I’ve got their catless set on my car. No issues what so ever. She shop that installed them said they fit better than many of the more expensive brands.