Race Tires?

I just purchased some 2003 Hed 3 clincher wheels to use for races (Olympic
distance and longer). They came with Vittoria 20mm tires. I'll probably
replace them before my key race (1/2 IM) in August. Is this a good choice for
these wheels, or would I be better off with a 23mm tire (I've always used
Continental and Michelin before)?

Thanks