NEW YORK: Sirius Satellite Radio has upped its year-end subscriber forecast to 6.3 million, an increase of 300,000 on its January projection and 100,000 above a forecast in May.

The forecast contrasts dramatically with that of rival XM Satellite Radio, which last week slashed its year-end subscriber forecast to 7.7-8.2 million from its earlier projection of 8.5m.

Sirius' not-so-secret-weapon is foul-mouthed shock-jock and audience magnet, Howard Stern, recently absconded from CBS Radio. Gushes Sirius ceo Mel Karmazin: "This year we have the best [expletive deleted] salesman on [expletive deleted] radio selling subscribers for us."