I'm just about to copy macspeedy and buy my manifold from SS headers but they have two options, a 4-2-1 and a 4-1, and I just wondered if anyone had opinions or knew what the difference is between the two??

The cost is only about a tenner different so not worried about that, just what power output diff (if anything) would be?

The original ZX12R system is 4-2-1 which gives the best power delivery through the rev range. Having said that, a badly designed 4-2-1 will be worse than a good 4-1. It depends on the bore diameters and lengths of primaries, collector and secondary pipes.

Phil

I can never rememebr which way round it is... 4-2-1 is better for top end power and 4-1 is better for midrange.

might be the other way round, but to be honest I doubt it matters hugely. If you get anyone who can rememeber which way round it is then I would go for the midrange one - as in a BEC that will be used more than outright top end power.

Other way around, you can tune 4>1 for max power, you can tune 4>2>1 for max torque and power in mid range but its a black art.

I made 4>2>1 same as the bike but used larger bore tube than the original.

There's some good information regarding BEC exhaust systems on Richard Miles superb website.

Here

Phil

I brought some stainless steal 4-2-1 headers, which included a lambna boss for a £295 from mk, with the current exchange rate with the dollar the ss headers don't seam such a good buy when you add postage and inport duty.
Just a tought.

[Edited on 3/1/09 by eddbaz]