The answer to your question is contained in this video, which should be played at high volume: http://www.youtube.com/watch?v=C1CPD17Pwzc
....so you didn't believe the answers you got on the other thread you started, asking the same question?
Tis really hard to have dual exhaust from a single header. Not impossible but if you are going to split them anyway why not get it done up front. Don
Or use the search feature up at the top, I wanted to ask a few 235 questions myself but they have already been answered in great detail. Besides, some people seem to get grumpy if you ask a question more than once.
More power can be had by keeping 1,2,&3 and 4,5,&6 different all the way back. no X-pipe, no H-pipe, no Y-pipe, ect... or so I've had pounded in my head over at the inliners site...
It is a different question on a race car and a street driven car. If it's your driver you need dual pipes. What else? On a race motor 6 into one may well be a better deal.
75% of the responses to his first post (75% at this time) told him to post the question here, rather than in the intro section. Could that be the reason for the new thread? At least this FNG listens, some of them come storming in like they own the place. Split headers, for sound and a little more HP, depending on how restrictive the 6:1 is that the header is replacing. Combining 123 and 456 into separate headers give you 180 degree headers, where exhaust pulses from each of the three sets of cylinders (front and rear) are spaced evenly for the best possible scavenging. Not to mention that they sound like the cat's ***.