Rockers System of a Down have added a half-dozen new cities to their upcoming North American tour, which gets underway in early August.

Newly announced stops--for which tickets will hit the market over the weekend--include Phoenix; Pensacola, FL; Orlando, FL; West Palm Beach, FL; Montreal; and Quebec City, Quebec.

SOAD's website is hosting a ticket presale; details are posted at the site.

The tour, which will feature special guests The Mars Volta [ tickets ] on all dates, is expected to touch down in about 40 cities over 10 weeks, according to organizers. Bad Acid Trip will open the tour's first leg.

System of a Down's latest release, last month's "Mezmerize," sold 453,000 units during its first week in stores, enough to score a No. 1 debut on The Billboard 200 album chart.

"Mezmerize" is billed as Disc One of the two-disc set "Mezmerize/Hypnotize." The "Hypnotize" half of the set is expected to hit stores late this fall.

The Southern California-based group recorded the 30 tracks that comprise "Mezmerize/Hypnotize" at co-producer Rick Rubin's Los Angeles studio during the second half of 2004. Andy Wallace mixed the set.