The net subscriber growth of 373,064 puts the New York-based satellite radio operator over 20.5 million subscribers (20,564,028) for the first time. That figure is up 9% from the 18.9 million subs of a year ago. The company also reveals that its "SAC", or subscriber acquisition cost, continues to drop, from $59 to $57, and the churn is stable, at around 2%. CEO Mel Karmazin says "we operate in a highly competitive audio environment, yet consumers continue to choose SiriusXM."

Free cash flow improved from a negative $127 million last year to a negative $17 million, partly driven by lower costs related to satellites. Net income nearly doubled, from $42 million last year to $78 million for the quarter that ended March 31. That's equal to 1 cent per share. CFO David Frear says "we ended the first quarter with $434 million of cash and cash equivalents" after using $135 million to buy back debt. The leverage (net debt to adjusted EBITDA) improved from 6.6 times a year ago to 4.1 times. SiriusXM sticks with its guidance of achieving $3 billion in total revenue this year and adjusted EBITDA of about $715 million. Subscriber-wise, it believes it can add a total of 1.4 million subs in 2011, and should generate a better-than-expected $350 million or in free cash flow.