The DLX 250 isn't a true 250cc, and depending on the speeds you're hoping to maintain, it might be better to look at another brand, perhaps GPX? They're Chinese made, but they seem to use top shelf stuff, and they have an air cooled dirt bike that is a true 250, and also a liquid cooled 250 that's fuel injected, if a bit pricier, which has the same motor as the RX3. They're twice the bike of anything Japanese offered at the same price point:
https://gpxmoto.com/