I've read that pretty much anything from Rick's is awesome quality, so this header's quality isn't what I'm questioning.
I know that this header gives best mid-range gains, where it is needed most, but does it actually lose a little top end power, or does it just not gain as much up top as in the mid-range? This can apply to the Mugen header as well, so any owners of those feel free to chime in.

 

Oops, I thought this was in S2k Talk. Someone please move

 

Moving

 

In the case of our test car (mine) the air/fuel ratio was very rich at the top end, that acounted for the lose of power seen on the dyno plot. It ws suggested that with proper tuning, that power could continue to be had up top.

 

def a mid range power boost now

 

If it's running richer than stock up top doesn't that suggest less air flow from the new header?

 

^ you've got it right. But a 260USD VAFC2 will lean that area out and make power. If I would buy a header today, this would be my top 3:

1.J's Racing
2.Power House Amuse
3.Spoon

 

So those three are more for top end power than Rick's/Mugen, I presume?