Don't know about the twinkies but I do know that I've used evo gaskets on my Shovelhead pipes in the past.

 

They were first used on shovels! I have heard of stock and CVO type gaskets, but can't confirm the CVO type.

 

The flat gaskets are the old stock gaskets it wasn't until like the mid 90's that they switch to a tapered gasket to go with the tapered seat of their header pipes. Not sure how a flat gasket could be too thick for the headers though, you kind of lost me on that comment as most AM pipes are designed for the flat type gaskets and not the tapered type. The SE gasket is just the flat type gasket and not the tapered. I have even been told by a dealer mechanic to use 2 gaskets if one continues to leak.

 

As said, either tapered or flat depending on the exhaust... The flats gaskets nor the port diameter have not changed in decades, however i have seen some flat gaskets that were not manufactured properly (cometic) And I sent them pics and they sent me back several pairs of the correct size.

 

 

I just looked at the Fuel Moto gasket kit and it comes with the flat gaskets, you may be thinking that they are thicker than normal but they are the Cometic flat exhaust gaskets.