I hope someone can share their knowledge to educate me on this subject. I lost sleep last night…
Why is a 4-2-1 header design considered to be the better design for a normally aspirated engine ?
and
Why is a 4-1 header design considered to be the better design for a supercharged engine ?
/Michael
Found some info on the subject over at team-integra, but sill not whu 4-1 is preferred with SC.
Unless you have tested both, on each configuration, with the ability to map the ECU properly, to take both into account, who’s to say which is better? 
The only way is what the OE do, and its a sort of trombone, sliding arrangement thingy, where they work out the optimum set up after days of work and dyno time, and days of computer simulation. Then ignore it anyway for packaging reasons.
I remember being at the dyno with someone who was very proud of their new design SC 4-1 manifold. After running the car to the optimum with their previous 4-2-1 system and mapping to suit. Swapped over to the new uber design, remapped and it made less of everything. Everywhere. They were really disappointed. More so as they had 5 in the car ready to go that were effectively worthless. Not a Lotus by the way.
Theory’s great in practice. Not always so much in real life.
4-2-1 flatter torque curve
4-1 more bhp at higher rpm
Or not
See above!
Been there spent £1k and made 2hp and lost torque in the midrange, it should have made more everywhere, just doesn’t work like that 
yeah unless you can make a modular rig, then try lots on a dyno, I’d just go with the flow (aww bad pun) and get whatever one else does.