Header Studs & Gaskets....Need some Help.

So I had new headers made with 2-1/8 to 2-1/4 tubes....With my old 2" headers I ran 3/8 studs in my aluminum heads in all positions. On my new ones, the middle two tubes I can't fit the larger nuts that close.The nuts hit the tubes....Is there any options to still run studs somehow?

Arp 12pt nuts? McMaster Carr also has 3/8studs stepped down to 5/16.
Or heat the tubes at the nut area and punch in some clearance.

I will check out the stepped ones from McMaster Carr....Hopefully those work....

Next question, where fo I get larger header gaskets? The TTI's don't fit, they are D shaped with the arch at the top and outside the flange, the Mancini remflex are too small...

Have you used or tried the Mr. Gasket M.W. header gaskets yet
I used the 7/16, 3/8 or the 5/16 wrench size header bolts on my big tube step headers
I haven't used the ARP 3/8x16 header studs though

No, and Mr Gasket is like low on the list like Walmart. Most items I have purchased from them are just junk.

Seems switching to the larger headers is causing all my normal stuff to not fit.

Their, Mr. Gasket, Ultra seal header gaskets work good, not real cheap either
How about using the Rem Flex 440-1 copper header gaskets Their oval shape, not round and not rectangular either

Looks late for this, but with them off, put a bolt through, and then progressively beat larger and larger tubes over it till you have room for the nut, The small dimples won't hurt a thing, except the finish lol.

Just use copper high temp RTV. Maddog header suggested it to me a few years ago and have had no issues with it yet. Let it set up over night and your good.

That has crossed my mind.....

No gaskets needed . Red hi temp silicone and that’s all you need

Take some hex stock, and turn the hex to the o.d.you need. The oem manifold nuts were like this.

don't forget to split the flange between the front/rear tubes from the center tubes and drill one hole on each set of flanges a couple of drill sizes over.
this allows the individual pipe[s] to move around a little, helping a bunch to keep them sealed to the head.
i stole this idea years ago from mr. P-body, and it has done wonders for sealing, using gaskets or just plain hi-temp RTV.
works really well on thin flanges to keep them sealed up.