In 2002 Grossi re-located to Los Angeles and quickly became one the hardest working guitarists in town, eventually landing him the guitar spot in Quiet Riot when the band re-formed in 2004.

Grossi toured with Quiet Riot in 2005 and 2006 throughout America, Europe, South America and Asia and contributed songwriting on the songs "Free" and "Strange Daze" for the 2006 Rehab and joined in for the album's 2007 tour, which included feature slots at the 2007 Sweden Rock Festival as well as the first annual Rocklahoma Festival.

Grossi has also written, toured and recorded with such artists as Bang Tango, Steven Adler of Guns N' Roses, Adler's Appetite, Jani Lane of Warrant, Beautiful Creatures, Love/Hate, Skid Row, Dizzy Reed of Guns N' Roses (in Hookers & Blow), Orange County hardcore band Ignite and Elektra Records singer/songwriter Aimee Allen.

The song was released in conjunction with Adler's New York Times Bestseller tell-all biography "My Appetite for Detstruction: Sex, Drugs and Guns N' Roses" and debuted on The Howard Stern Show in July.

On September 13, 2010, it was announced that Quiet Riot would be reforming with the line up which would include Grossi, Frankie Banali and Chuck Wright.