Has anyone found a good aftermarket headgasket for the 20 valves?

TRD or Toda??

cometic maybe

TRD isn't aftermarket but thanks for reminding me about Toda.

Cometic doesn't have anything listed on their sight, nor does HKS japan. I might call them and see.

Does anyone know if there is anything that prevents a gasket being made that would work for all 4AGE? I know there are some small changes in oil and coolant ports but would it be possible to open them all or to do it in a way in which it would work for all configurations?

Power enterprise also has headgaskets for the 20V

TRD is mls and oem is not so I would call that aftermarket
Stolen from Bill Sherwood note the large coolant openings at the rear of the lower gasket(16v)

http://www.billzilla.org/4agegaskets.jpg

Cometic does have 20v gaskets I have one on my head....they still list them as 4ag u have to call and be specific about what model u want