Sacto Mitch posted:
Some folks with A1 Sidewinders have had custom mufflers made that tuck up under the rear valence and don't interfere with the valve covers.
I think the extractor headers themselves don't interfere.
It was the famous author @Terry Nuckels who best described this in his stream of consciousness novel, As I Lay Wrenching.
I've built several A1 sidewinder exhausts that have no interference issues. and tuck completely out of sight.