I remember this being posted on H-A, but I don't remember it being answered

4-1 vs 4-2-1.

Are there any pros and cons to each design?

 

My general understanding has always been that the 4-1 design is better for high rpm power and the 4-2-1 will show better gains in the midrange. My experience with the Comptech 4-2-1 header held true to this theory with a noticable mid-range power increase on my Type-R.

 

The only one for the S that has PROVEN power gains is the Mugen setup. Spoon and HKS people have not raved about it.

 

I am getting the mugen, as I know from all my reading, it IS the header to have for this car.

I was more interested in why some companies make their headers as a 4-1 and some make 4-2-1

 

Actually, many companies make both versions. You would choose depending on use. I went with a 4-2-1 on my Type R because I wanted usable power gains on the street, not something I had to race on the track to enjoy. That was also decided with the recommendation of the person I talked to at Comptech.