[olddog]

That is the way my pipes are. The O2 bungs are welded in about (estimated not measured) 14" from the head in a single pipe. I have read many sources who claim it is better to use a single pipe and stay within 18" of the head, than to use a collector 30" from the head. Obviously it is best to have all pipes merged together closer to the head, but that isn't going to work with Cobra side pipes.

Using a single tube means you need a very ballanced air flow on both intake and exhaust side to keep all cylinders equally rich/lean. A bad injector on the cylinder with the O2 will mess up your day too.

Now I saw quite a few Cobra with the O2 in the collector on the side pipe. A couple of the guys I questioned are using a system that has a wide band O2, not the narrow band O2 used in the OEM applications.

I'm far from an expert, and I have pretty much told you all I know. Hope it helps.