To clarify the 4-1 vs 4-2-1 subject...
From DC Sport's web site:
What is the difference between a 4-1 header and a 4-2-1 header?
Answer
In many cases 4-1 headers are designed for racing applications where the vehicle is being driven at or near redline. The 4-1 design maximizes top end power, whereas the 4-2-1 evenly distributes it throughout the power band. There are cases where a 4-1 header works better than the 4-2-1 and in those cases we use this design.
http://www.dcsports.com/faq.asp?fid=26&sid=&tid=5
In other words, for race get 4-1, for every day street use, get 4-2-1... Course it is all about personal preference...