I had Delkevics in my ST1300 (Version 1), got 'em off a member in Armidale NSW, picked 'em up on my long road to the 2023 NatRally at Mudgee,put 'em on the bike, a lovely, deep, throaty, very loud roar when the throttle was used hard, a bit too noisey for the pillion's liking, even under gentle throttle.
Took 'em off to get the VIV certificate in March 2024 (general consensus that it would be easier to get the VIV with the bike back in originals specs), they're now in Brisbane with Cerebral Knievel, 'spose he has on a bike.
No idea what inserts were in 'em.