I replaced my 318's stock exhaust manifolds and the 2.25" flow masters the other day.
The old Demon 625 cfm carb got the axe too, now she's got a 600 cfm Holley Carburetor. TTI ceramic long tube headers, X pipe, Hooker Super Competition Max Flo Mufflers, 2 1/2" X pipe help the business end of my mopar breathe.
Sealing up the headers are those Remflex gaskets, so far so good. I've got it scheduled for the dyno shop in a few weeks. I think the timing may need a little help.
Here's a video I made:
https://youtu.be/YvKz5oL5emA