From what I have heard, 4-2-1 gives moderate top end power, while also focusing on power throughout the range, moreso than a 4-1.
A 4-1 header is more about the top end gain, but will still gain some power.
I say, the 4-1 header is made for your car, but the question is, Do you drive your car how it was meant to be driven?
If yes, go for 4-1.
If you would like to see a considerable all around gain, for daily driving then the 4-2-1 is for you.
There are alot of opinions on this matter, and the roots go alot deeper than 4-2-1 vs. 4-1.
Basically, what do you want from a header, all around gain, or a big bang up top?