I have a 1992 honda civic hatchback with a jdm b16. I have my stock radiator and fan, and ac lines and condenser. Im looking for a 4-2-1 header that has the clearance for the radiator and condenser.

 

Th the best *commonly available* headers I've seen are the PLM RMF narrow rep and the Toda or PLM Toda rep.

The Toda/rep clears everything as is. Makes good midrange...but really shines up on the top end.

The RMF is more of a 4-1. It makes super healthy midrange and good top end. You have to trim the rad fan or use a slim fan.

I personally had the RMF rep on my almost stock 01 ITR (also had intake and high flow 2.5" cat). I trimmed my fan when I had a stock radiator and had 0 issues. I also had to trim a slim fan when I got a fluidyne radiator. Only issue was heat getting into the slave cylinder when I tracked the car hard. A little heat shielding and better fluid would cure it.

My friend put the Toda rep on my EM1 that he bought from me that had a 00 Spec R swap and an Endyn head and worldsport exhaust with test pipe. Maybe the combination of all that is why that car had such good top end.