I am building an h2b del Sol EG1. Wants to buy a header and looking PLM's headers.

They have two options: an h22 4-2-1 tri-y and an h2b 4-2-1 header which have longer tubes and is bended for h2b setups.

The tri-y header, the primary tubes are shorter and it merges cylinders #1&4 and #2&3. Previous experience and reading tells that this is the correct way to do it.

The h2b header have longer primaries and it merges #1&2 and #3&4.

My concern are both, an engine that is more "inclined" to produce low to mid range torque should have shorter primaries, and 4-2-1 headers should merge #1&4 and #2&3, if the firing is 1-3-4-2.

Please comment with facts & knowledge...

h22 Tri-y

H2B header

With how much low and midrange torque the H series has, and how light your chasis is, I wouldn't worry about header length, especially since this is not a custom header for your particular motor. That's just me though, you do what you feel you need to. Also, just because a motor is "inclined" to produce more low and midrange power, does not mean shorter primaries are necessarily better for it. Header design depends on your personal goals for engine characteristics.
That said, I would agree about the cylinder pairing, the 1&2, 3&4 is kind of funky. There might be something to it though, maybe someone who knows more about cylinder pairings than I can chime in

From "Honda/Acura Engine Performance:..." by Mike Kojima-
"A well designed collector pairs cylinders opposite in the firing order with each other so an exiting pulse from one cylinder will not hamper the evacuation of the next cylinder. Adjacent cylinders in the firing order are kept separate so that the exiting pulse of one cylinder cannot contaminate the next cylinder that may be on the overlap part of the power stroke. In a typical inline-4 cylinder, that would mean pairing cylinders 1-4, and 2-3."
In other words, the wave tuning of the PLM H2B header would be all mumbo jumbo and would probably perform worse than the tri-y. After looking at the PLM H2B header, I'm thinking that cylinder pairing maybe used for better clearance, as the header might run closer to the block than with the other

[QUOTE=TracerAcer2.2L;49832201]Adjacent cylinders in the firing order are kept separate so that the exiting pulse of one cylinder cannot contaminate the next cylinder that may be on the overlap part of the power stroke. In a typical inline-4 cylinder, that would mean pairing cylinders 1-4, and 2-3."/QUOTE]

Agreed with it. I think thats why it does have longer primarys, to help avoiding that one cylinder affect the nextone.

Ah yes, probably. If it bothers you, maybe look into High-End headers as well, I think they are comparable in price and quality

Any other had proved those two headers?

Hey man, I'm sure you want to here from someone else, but later on as I was researching headers I came across some more information on pairing 1&2; 3&4.
See, I knew that h2b design looked familiar, it's because that's a SMSP replica. SMSP for some reason does that cylinder pairing; I believe with that pairing, coupled with the very long primaries, produces a flat torque curve and good low and mid range power without sacrificing much on the top end.
This is because negative exhaust pulse waves are "absorbed" and partially "cancelled out" by the "dead" cylinder, thus decreasing reversion interference (but thats a lesson for another day.
In short, I don't know where my brain went the other day, but assuming the dimentions of the header suit your motor's build, you should find significant gains even with that exhaust pairing. Hope this sheds some more light on the subject

Edit: I've seen SMSP comment on another thread before that he likes a big flat torque curve, which is why I believe his design produces those characteristics specifically

Highend is the best replica for H22 motors. Proven many times.

Any comments about PLM h2b header?

Search. I've looked for dynos on them many times, you will find what you're looking for