Who was the first to use "tuned" equal length 4-into-2-into 1 exhaust headers on an automotive engine? And when? Also known as "extractor exhaust".
Maybe Gordini?
Anton

There's some useful info in this earlier thread:

Exhaust systems

I'd say Ed Winfield mid 30s, for Rex mays and his Legion Ascot "Winfield Special"

For those who can't be bothered with the linked thread, we had this as potentially earliest:

The 1906 GP Brasier was a four in the dimensions of 165/150 mm delivering 105 hp at 1380 rpm. Its exhaust manifold combined cylinders one with four, and two with three.

But thats not 4 into 2 into 1, is it? Also, I doubt the head pipes would of been of equal length.

There was a photo, but it's gone. That's the trouble with linking other sites of course.
The junctions of the 1/4 and 2/3 pairings were half-way along the engine, so the pairs certainly were equal length. I think that the 2/3 junction was outboard of the other, so maybe all pipes were equal (ish).
The photo did not show where 2 into 1 bit would have been, if it existed, so we don't know.

Very much OT, but Ron Tauranac told me that when they were creating the exhausts for the F1 Climax-engined Brabhams, they filled each pipe with ping pong balls (quite similar in diameter to the primary pipes) to check if they were of equal length.

Ain't science wonderful

Nice lateral thinking anyway! A friend of mine and I made quite a good exhaust manifold for a tricky installation (Lancia Fulvia). We agonised about how to plan the pipe runs and came up with the solution of buying some vacuum-cleaner hose. This we cut into the appropriate lengths and fiddled with it, taping it up with masking tape until we had a prototype!

Paul