His first professional engagement was playing boogie-woogie piano with Mel Torme on drums for a television pilot at the age of five, filmed on location at Bimbo's 365 Club in San Francisco.

At age ten, he was given a set of Slingerland Radio-King drums by actor Jack Webb of Dragnet, a noted jazz aficionado.

By age nineteen he was playing drums with Los Angeles-based singers Pat and Lolly Vegas, whom later formed the pop/rock group Redbone.

[3] Kowalski, along with the Vegas Brothers and several players from The Wrecking Crew, recorded "Laugh At Me", Sonny Bono's only hit song as a solo artist.

On January 3, 1968, Kowalski flew to London to join guitarist Ed Carter's blues rock band, The New Nadir, with Gary Thain on bass.

The trio shared the bill at the Marquee Club with Jethro Tull, Ten Years After, The Nice, the Aynsley Dunbar Retaliation, and the Jeff Beck Group, to name a few.

Kowalski and Carter returned to Los Angeles, while Thain remained in London, eventually gaining recognition with Keef Hartley and Uriah Heep.

Bruce Johnston suggested Ed Carter for bass and guitar, Doug Dragon for keyboards, and Kowalski for percussion and drums.

After touring with the group as a percussionist in 1968, Kowalski played his first show on drums at the Big Sur Folk Festival in Monterey, California on October 3, 1970, filling in for Wilson, who was then filming Monte Hellman's Two-Lane Blacktop (1971).

In 1971, Kowalski was again on drums as the Beach Boys performed a slot at the invitation-only closing night of New York City's Fillmore East on June 27 and filmed the NBC special Good Vibrations From Central Park on July 2.

By the end of the year, Kowalski and Wilson, who was back on drums, performed during the band's controversial holiday engagement in apartheid-era Sun City, South Africa.