Kenda booster & rush. Continental race king. Maxxis Aspen & Aspen ST. Schwalbe RRs, Vittoria Mezcal, S-works Renegade & fast track, Pirelli Scorpion. Basically every MTB tire manufacturer makes an XC race tire in the 600g range. Some are below 600g, some are above 600g (but below 700g). Just look at the list on the website this thread is under.