Not to be mean, but this has to be the fifth header thread in the last month. There is a search button at the top of the page. That being said, I run two thorley tri-y headers. They work well, although I haven't tried a four into one yet. One of those thorleys has been a pain to keep sealed at the head, and is almost pointless to seal up at the collector. The flanges are kinda thin. I just bought a NWOR header off ebay, but haven't installed it yet. The flange is massive at 1/2" thick. When I replace the thorley on my 89 2wd, I think I am going to try a LC Engineering header.
I replaced the manifold on my 4wd because the collector studs kept breaking or loosening up. And a header is typically lighter. And easier to repair
