I have an eg civic with B18C5. I know the 4 to 1 header gives more high end but looses a lot on low end. How is the 4 2 1 in comparisson?

 

4 2 1 is way better for the mid range and will give you a little more low end than the 4 1

 

You don't need the 4-1. You'll kill your midrange unless your are seriously putting down some power.

 

I am pretty sure that most of the good headers out there are all 4-2-1, take a look at that comptech race header, its a 4-2-1, I think the hytech and smsp headers are 4-2-1 also. Plus they have better ground clearance.