Remember, the B20a5 header does not fit on a B20a3 cylinder head. We need a readily available performance header for the B20a3 and other SOHC 3rd gen Prelude cylinder head.
As I was poking around online, I stumbled across this:
OBX RACE EXHAUST HEADER 84-87 HONDA PRELUDE 2.0L A20
I know there are a lot of similarities between the A20 and B20a3 cylinder heads and PGM-CARB setups. It would not surprise me if they are almost identical in a lot of ways.
So I invested $10 in a Felpro exhaust manifold gasket made for a 86 Prelude PGM-CARB.
It fits like the regular B20a3 exhaust manifold gasket. Exact match. Now the only thing to figure out is if the header angle is compatible with the angle the B20a3 sits at. If the angle is right (or close enough), we have a bolt-on performance header options. If the angle is too far out, we could possibly modify it to work.
Adjustable Cam Gear too:
Also a side note, here is a F22 adjustable cam gear I bought off eBay for my B20a3 build. I took a gamble on it and found it is an exact fit with the B20a3 cam gear. The only questionable remark I have is regarding the quality of design. The generic eBay cam gears suck.
In any event, even if this cheap cam gear slips, the B20a3 is a non-interference engine. Meaning under any stock circumstances, a valve will never be able to kiss a piston.
In my particular engine build, I am milling the engine block and head surface down for performance, so I don't know if it will change anything.