Ok...who makes a good one?? and i mean like Smith Innovations. He just called me and he is not making them anymore. Im looking for something sturdy 3/8 something thats 2 1/4 and something thats not hard to get a tube into. I dread putting a round peg in that square hole ... Oh yea an stainless steel too.

Thanks

SPD Exhaust..

yep


http://www.spdexhaust.com/Header-FlangesB.html

Stainless Headers has some good you tube video's showing how to put a round peg into a square hole.

they used to be real pretty but I cut them apart to make things easier





Untitled by John Cadamore, on Flickr

You will have to do some amount of "squaring" or flatening the round tube to put it in the header flange. You run out of room on the head, so the flange needs to be less than 2.375" tall and a round 2.25" tube opening won't leave much for sealing above/below the port.
Attached picture from SPD

FWIW,
My heads were ported by the previous owner/shop. It may have different dimension than yours.
I had a local laser cutting shop make a couple pairs of flanges (mild steel). And I made a simple jig to "form" the tube to the flange shape. It still takes some hammer tapping and peening before welding.

But I am happy with the result. My headers are finally finished welded....

Your could "borrow" the forming tool (used in a flat faced vice).
But it is made for the flanges I have.

I love the tool! I need to make one

I suggest making the height of the forming tool roughly 0.035" less than the height of the flange opening. The vice pushes the tube flat, but it can spring back somewhat.
The center body (green) helps to prevent the flat part of the tube from "buckling" or bending toward the center as the tube is formed.