I have a 73 240z. I am looking for a header to replace older rusty warped header. I ordered a Pacesetter from Black Dragon(Victoria British). When I placed the order they asked me whether I needed square port or round port. I advised them that I needed square port. When I received the header, it has ports 1,2,5,6 as round ports and 3,4 as square ports. I called back to Black Dragon and asked them about the difference and they told me that is what they had. I had them look at the catalog that clearly shows the gasket with all square (the gasket ports are the same as the header they sent me) and they said that it must be a misprint. I then called Pacesetter directly and they told me that they are now making this header this way so it will be universal between the square ports and the round ports heads. I explained that putting on this round port header would cover some of the square exhaust ports and they told me that it would not matter. Really??? Pacesetter also told me that they have 240z race teams that buy these headers and swear by them. Pacesetter's part number is 70-1037. I would think that first of all it would blow out the gasket if the gasket is round and not as big as the square port and I dont want to restrick the airflow coming out of the exhaust. Has anybody else heard of this. I need to find a header or manifold that is not warped for my car. I don't have alot of $ to spend and need to get my car back on the road. Please help.