I used them in the past. They fit real nice and install fairly easy. Several of the tubes come out to ease installation. The only thing I recommend is to cut the flange between each of the ports to prevent the flange from warping. The flange is thin because it is a cheap header. Thin flanges do warp sometimes and cause leaks. If you cut them so each port is individual you will prevent warping.
I guess you would never buy a set of Lemonds or Kooks headers or any other big name headers than. Slip tubes do not cause leaks and the majority of the big name headers have slip tubes or slip fit collectors.Not a big fan of the slip tubes it always sounds like I have a leak.