Vittoria valve extenders do not work - in my pack of two, both were duff
Forgive me if I'm teaching you suck eggs but they were extenders and not the interchangeable valves for their tubs? I've seen a few people trying to use the red tub valves as extenders at the velodrome.
I use the vittorias and get on fine with them. Got a few on sale for £6 a short while back. Have only ever found them with a 48mm valve.
(Vittoria valve extenders do not work - in my pack of two, both were duff).