Round 16 for the GTS category, held on Sunday morning at Sonoma Raceway, saw Michael Cooper victorious in the No. 10 Blackdog Speed Shop Chevrolet Camaro.

Andy Lee led the field through Turn 1 in the No. 20 BestIT Racing Camaro following the standing start with Cooper in the No. 10 Camaro right behind. Jack Baldwin, at the wheel of the No. 73 GTSport Racing Porsche Cayman S slotted into third at the earliest stages of the race.

Shortly after the start, Baldwin was issued a drive through penalty from Race Control after he spun during the formation lap and moved to regain his starting position for the standing start, going against the rule outlined in the series rule book. After serving the penalty, Baldwin fell to the back of the pack in the No. 73 Porsche.

Cooper took the lead from Lee at the end of the opening lap at the Turn 11 hairpin just before the run to the start/finish line.

On the second lap, Kurt Rezzetano, at the wheel of the No. 37 Phoenix American Motorsports Ford Mustang Boss 302, made contact with the No. 36 Kinetic Motorsports Kia Optima of Ben Clucas, resulting in them both going off track at the Turn 6 carousel. A full course yellow was issued to get the cars back on track.

During the yellow period, Cooper remained at the front, followed by Lee, Wilson in the No. 07 TRG-AMR Aston Martin Vantage G4, Andrew Aquilante in the No. 32 Ford Mustang Boss 302 and Mark Wilkins in the No. 38 Kia Optima rounding out the top-five.

On the restart at Lap 5, Cooper got going well and led Lee, Wilson, Aquilante and Wilkins to and through Turn 1.

By Lap 9, Lee had closed in on Cooper, with these two well ahead of Wilson and Aquilante in third and fourth. Unfortunately for Lee, though, as he entered the carousel on that lap, his No. 20 Camaro suffered a mechanical issue, forcing him to pull off track and bringing his day to a premature end.

With Lee out, Cooper then led over Wilson, Aquilante, Wilkins and 15-year-old phenom Nathan Stacy in the No. 14 Rehagen Racing Ford Mustang Boss 302 rounding out the top-five. Cooper, running second, built up a six-second lead over Wilson and Aquilante who were running nose to tail. Baldwin, following his earlier penalty, had charged all the way up to seventh.

On Lap 14, Stacy put the No. 14 Mustang into fourth position as he got by Wilkins at the hairpin. Three laps alter, Baldwin continued to move forward, passing both Wilkins and Nicolas Hammann of the No. 23 Skullcandy Team Nissan Nissan 370Z at Turn 7a/7b. Then, on Lap 19, Baldwin got by Stacy in the same corner for fourth.

At the checkers, Cooper won his fourth GTS class race of the season with Wilson and Aquilante rounding out the podium behind him and Baldwin fourth followed by Stacy in fifth.

With two wins at Sonoma, Cooper remains at the top of the Drivers' Championship points with 1,475 over Aquilante with 1,368 and Baldwin with 1,320.

Next up for the GTS class is the finale weekend of the 2015 season, which is set for September 11-13 at Mazda Raceway Laguna Seca.

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Aaron Durant is the editor of the VAVEL USA Racing section. Follow him on Twitter at @DoubleA291.