I've riden everything but the international at Buller, I'm guessing that's what the race will be on.Absolutely. There’s a very competitive short travel separate class...but many ride enduro bikes in all categories.
If you’re old (above 15 ) and new to DH, race Sport class on your Enduro.
Depends on track, too. Buller more suited to DH bike, but absolutely fine on 160mm.