[What'saCobra?]

Really big and controversial subject, but here is at least one or two thoughts.

Years ago i had one of the team FIA 289's, both for eventing and the street. It had a true 180 degree header system fabricated by Belanger, if i recall, in Gardena or somewhere. The inner two cylinder's pipes traveled down the block and under the engine/pan/chassis rails and connected with a header on the other side, along with the two outer cylinders. And visa versa. So, 4 pipes travelled left to right under the car, all 4 being inner cylinders. Sounded really nasty at high rpm and shook the ground at low.

On the street i used simple open glass pacs, that constantly needed refilling. But they worked very fine indeed. Nicely smooth and purring at low rpm and gnarly at high.

Of course, the car had low ground clearance and i wouldn't suggest streeting it in NYCity.

Never saw another pair in my life. Anyone else remember?

Secondly, take a look at the 'augmented' exhaust collectors of either a Beech Twin Bonanza or an older pre-Rockwell AeroCommander. (And a few other old North American products.) They were big straight tubes that simply surrounded the open-ended and different lengthed pipes on each side and they sounded quite nice on the ground, from 540 in3 engines, both at idle and takeoff power. The same concept might be applied and i did so on a 427 center oiler of about 1968 or so. They worked fine and didn't need rebuilding so often. They did look different a bit, but not radical and they were effective.

Of course, these are both for experimental and racey engineers and not suggested for conaseurs of hysterical cloning exactitude.