Well im looking into replacing the DC Sport 4-2-1 header that came on the car when i purchsed it. Out of these two which will give me the best gains.

Current mods are I/H/E, planning on a set of cams and other mods.
Goal is 200whp

 

both are great but RMF gets my vote

 

IF you are looking for peak horsepower you will be better off with a 4:1 header a 4:2:1 typically produces a broader more useable powerband

Both header are quality and booth randy of RMF and john @ hytech are some very knowledeable guys

 

There will be some more testing happening mid July on a somewhat built (bolt on) B18 so you may want to watch for it over in the all motor forum.

 

OK thanks for the info. Hopefully i'll make my mind up soon. Also, a 17" long, 2.5" cat will be need in conjunction correct? My exhaust is USDM length.