Throwing my hat in the ring here. This is my 2nd version of a custom EJ22 singleport header. This one is based on the Cobb/Brullen/OBX equal length header for the NA EJ25's. Nobody makes one for the singleport, so I made my own.
On the jig, tacking things up.
Initial fitment showed that I put a reference point in the wrong spot on the jig, so my 45* tube had to be rerouted to go straight back and over toward the collector before merging in. The finished piece ended up like this.
Primaries are 1.8" ID 304SS collected into a 2.25"ID section. Primaries seem large because they're each handling 2 cylinders right from the head. Runner lengths are within 0.5" of being equal at about 44" long. Butt dyno says this one is at least as good as the MRT style longtube header I made a couple years ago, both of which are head and shoulders better than the OEM manifold.
Might as well show my 1st attempt at custom header fabrication. Complete with fluxcore welded 304SS!!! It never broke on me, which is alot more than I can say for the couple Borlas I've had through the years....