whats better/differences between a 4-1 header and a 4-2-1 header. i hear ones better for low end and the other vice versa. thanks for help.

 

This is a long standing myth. The piping design and primary length have more to do with power characteristics than 4-1 vs. 4-2-1. If you want to make power, get a good quality header. JDM 4-1 or DC JDM if you're on a budget ... HyTech, SMS, or TODA if the sky's the limit.

 

collector is bigger on 4-1 vs. the 4-2-1

 

Not necessarily. The brand and model of header determines the collector size used.

 

hmm... well if the 4-1 having better low/mid end and 4-2-1 having better high end is a myth in general, maybe we can point out the ones that have these characteristics.

So which header has better low-mid end power, and which have better high end?

 

How I know it, 4-1 for top end power and 4-2-1 for mid power gains

 

Here's a couple of links that show a large number of headers and their characteristics:

http://honda-tech.com/zerothread?id=700477
http://www.honda-tech.com/zerothread?id=699674&page=1

unfortunately, all the actual dyno plots in the second link appear to be down. if you're interested in seeing them, email James at Titan and see if he can get them back up.

from my experience, it seems as though headers that possess a 4-2-1 design with stepped primaries (i.e., the diameter of the piping increases as you go from the flange to the collector) and a single wall collector have the smoothest overall power curve and they allow for a lower VTEC crossover in a basic i/h/e set-ups.

once you start throwing in cams, IMs, TBs, etc., things change though.

 

What's the best header for, say, my friend's LS? He's asking about low- to mid- gains.

 

why does he want low to mid gains when he wont use any of low and hardly any of mid when he is looking for those gains. 4-1 is the best performance header bar none. now for grandma driving the 4-2-1 is better.