Wales claimed a second championship in three years after France's defeat to Scotland in the last game of the tournament on Saturday (AEDT).
Pivac's men lost just once in the campaign, to Les Bleus a week ago, and scored a tournament-leading 20 tries in five matches after winning just once in last year's competition and only three times in the whole of Pivac's first year in charge.
"We're not the finished product. We will keep improving and fine tuning," Pivac said.
Wales scored seven of its tries against Italy but also scored four against England and finished the competition by running in three in the loss to France.
"With no disrespect to the Italys of the world, scoring a few tries against a side like that, you have to back it up against a quality team like the top two or three teams in the world," he added.
"And doing that against France, albeit if we came up short, gives us a lot of confidence to think we're on the right track."
Pivac is scheduled to take his side to South America during the summer for its next Test matches, but the New Zealander said the coronavirus pandemic could hamper those plans.
"Those discussions are ongoing and I'd like to think that over the next week or two we'd be in a much better position to talk exact opposition and dates," Pivac said.
"At the moment it's Uruguay and two Tests in Argentina. We have to make sure that everything meets up with the (UK) Government in terms of COVID.
"It's a moving thing we discuss on regular basis."
Wales was handed the trophy in a ceremony at its training base outside Cardiff overnight (AEDT).
Captain Alun Wyn Jones celebrated his fifth Six Nations win and Pivac his first.
Pivac said he hoped to have as many Wales players as possible in former Wales coach Warren Gatland's British and Irish Lions squad this summer.
"First and foremost there's a British and Irish Lions tour that Warren will select," Pivac said.
"We'd like to think that we'll get a good representative on it."
Pivac and his team were made to wait six days to clinch the title.
They were awaiting France's result with Scotland after the dramatic late loss in Paris a week ago which denied Wales the Grand Slam.
"It was an emotional rollercoaster, the last seven days," Pivac said.
"To lose it in the last play of the game was devastating. The boys really wanted that Grand Slam, so we had the lows of not achieving that."