I just got a set from e bay / Everett power sports Buick shipped great service nice people
Some hardware bags had David Silver spares ,pipes I thought came from Tiawanese Mfg.

No I'd type marks I'm surprised that someone doesn't make 4-4 systems,beautiful classic line to pipes upswept just right ,l can see that type pie on Mike the Bike Hailwoods 250 six
Sound little less than stock but better with baffles in??,interior of pipes seem to be different as I remember,back BTD it was all 4-1 stockers hanging in garages ever were in 1973
Just finished 1976 K-6 still a nice bike to ride after 40 years,sweet motor,