Comparison question: F22a6 vs F22a1/a4 exhaust manifold gasket

[HondaFan81]

I want reassurance on the F22a4 exhaust manifold gasket being the bestmatch for aftermarket tubular headers. I know that F22a4 is for the stock tubular header and has its own part number, compared to the cast iron manifolds for F22a1/a6 that haver their own part number. So there IS a difference between the two, I'm not 100% on what that is specifically.

My assumption is that the F22a4 gasket is more round in port shape designed for tubular header, unlike the a1/a6 gasket which is probably more oval shaped, etc.

Is my assumption correct? Should I get a f22a4 gasket for a aftermarket tubular header?

[bjaccord]

Also, the H23a1 gasket is the same part number as the a1 and a6. So the a4 is the only difference in the gasket part numbers, strange indeed though.

I wonder if maybe the a4 has an extra layer of material or maybe the port design is different, but for some reason I doubt that, as the head port is still the same size and shape from a1/a4 and a6.

Anyone else have any ideas?

[NAiL05]

Could it be the thickness of the gasket maybe?

[HondaFan81]

I checked on hondaautomotiveparts.com and both came back with the same part number for the exhaust manifold gasket.

Sorry bro, I already did checked that site for part number comparison before posting this thread up. They are NOT the same part number, according to that site. You must have checked wrong.

90-93 DX/LX are F22a1
91 or 93 SE are F22a6
90-91 EX are F22a4

[HondaFan81]

Also, the H23a1 gasket is the same part number as the a1 and a6. So the a4 is the only difference in the gasket part numbers, strange indeed though.

I wonder if maybe the a4 has an extra layer of material or maybe the port design is different, but for some reason I doubt that, as the head port is still the same size and shape from a1/a4 and a6.

Anyone else have any ideas?

Yea, I figured the f22a1/a6 and f22a4 gaskets are interchangeable on any f22ax head, but I'm thinking the ports are different shape.

[NAiL05]

Sorry bro, I already did checked that site for part number comparison before posting this thread up. They are NOT the same part number, according to that site. You must have checked wrong.

90-93 DX/LX are F22a1
91 or 93 SE are F22a6
90-91 EX are F22a4

Yea I forgot about the a4. I only did a1/a6. My bad.