Hey fellas. I just picked up an ebay header for 86 and some change shipped. I got it today. Measured it and confirmed that it's the 2.5" version. There are three more on there right now. You can see in the picture which one I'm talking about. They show the primary tubes at 2" and the secondary exit at 2.5"
I measured the primary and its 1 7/8" wide not 2". Close enough though. Flanges are 3/8" thick. It definitely looks like what the SSAC looks like. Box that it came in says dna motoring HDS- G2091
Just giving everybody a heads up. Not a bad mod for under 100 bucks.
I used "Sr20 header" as my search phrase.
Links to the auctions.