"[Saturday] was a challenge for all of us because it was the first time in the wet in the new car," said Bamber.
"But the car was amazing and it was definitely a great learning session for all of us."
For Sunday's race, Bamber got away well with Ragginger immediately giving chase, while Imperatori came under pressure from a hard-charging Avila.
With Avila trying to go around the outside, the pair made contact and the Macau driver spun out while Imperatori recovered immediately to hunt down the leading pair.
While Ragginger would set the fastest lap during the three-car shootout, Bamber kept him at bay, getting top spot of the podium and receiving his trophy from British actor Benedict Cumberbatch, star of the BBC show Sherlock and The Hobbit films.
The busy Bamber will now head immediately to Barcelona in Spain for Porsche Mobil 1 Supercup testing. "It was a challenge to hold off Martin [Ragginger] at the start, but by lap six we could pull away a bit," he said.
"It was just a matter of keeping my eyes forward, even though there was a big glaring gold car behind me.
"It's going to be close all year. I've had a bit more testing, but the others for sure are going to catch up."
Ragginger, who like Bamber now lives in Asia, vowed to close the gap in the championship points race.
"Our aim was as many points as possible in the first race as we have to get more used to the new car. It's very difficult to overtake as the cars are so equal."
Imperatori felt the same after his early contact with Avila cost him a chance to catch the top two.
"I had the same pace as Martin and Earl, but it's difficult to pass which is testament to the level of this championship.
"I pushed very hard on the last lap but Martin defended very well."
The next round for the 12th year of the Porsche Carrera Cup will be at the Shanghai International Circuit, again as a Formula 1 support race, on April 18-20.
In his debut last year, Bamber won seven of the 12 rounds of the cup and was only once off the podium.
He was then nominated to race in the Porsche Motorsport International Cup Scholarship challenge and emerged the winner, receiving funding of 200,000 ($327,000) from the factory giant for a 2014 Porsche Mobil 1 Supercup campaign.