stupid long or shorter headers?

[speedjohnston]

The flat 4 into one collector does not work well on a naturally aspirated car because you lose a lot of the vacuum effect of the exhaust pulse before it. When they are square the pulse before it helps draw the next through, but when they are flat the outside tubes are too far apart. Probably not the best explanation...
You will lose more power with the flat 4 into 1 than if you make long, short or improperly size primaries. If you are supercharged this is less important because you are forcing everything through from the other end.
If it was me, I would consider removing your bracing bars, build the headers the way you want and then see what you need to do to re brace everything. Mind you, I always seem to do what costs too much and takes too long so maybe don't listen to me. Lol