If anyone is interested, you can see what is needed to get the Knock offs cleaned up by visiting the "Cottons Performance" board. Go to the 4" down pipe thread in the "shop progress" section. Brian modded my knock offs when my GN was there for the down pipe. They (MAY) bolt to the heads, but the ports are off alignment among many other things. In fairness, I was going to hack off the turbo flange anyhow for a 4bolt, so I bought a set to see what it would really take to get them right. I'm anal about my stuff, so everything was massaged and modded. The crap v-band flanges and clamps were replaced with real stuff, tubes were cut open to clean up the welds/holes, head flanges were welded up and ported for perfect port alignment [outer ports were 1/4" off], and a 4 bolt turbo flange was installed. I have into these, what T/A's would have cost me, but the T/A's need some clean up also, and I would still have had to install the turbo flange. What I ended up with was a real nice set of port matched, custom headers for $1000. Also take a look at the beautiful Job Brian/Jack did on the 4"DP and external gate, while still retaining my heat/AC.