The Northern Ireland province have won seven of their eight games in the Magners League including their last five in a row.
They lie third in the Magners League locked on 55 points with Leinster and the Ospreys and face Scarlets on Friday night.
"I've watched Munster for a few years now and that's the thing about them, they're never beaten until the last whistle," Best told the Irish Times.
"There's no point ignoring what is very good about other teams and there's no doubt Munster have that.
"It's something that we've been trying to instil through Brian McLaughlin, 'hold on a minute, the game isn't finished until the final whistle', whereas in the past with Ulster teams, with five minutes to go and seven points down, not only do we not win the game, but we don't even get a losing bonus point."
Best admits the new hard-nosed edge is largely down to the influence of high-quality South African imports such as Ruan Pienaar who has landed last minute winners in three of the province's last five victories.
"It was quite hard for him when he arrived, especially in the position he plays in," added Best. "You don't just arrive and are brilliant from the start.
"We feel there is more in Ruan. He's obviously very well brought up, he knows how fortunate he is to have the ability he has.
"All he wants to do is use it to the best of his ability, and he's a very nice fella to have around the team. He gets on with his job but he's also starting to come into his own now, and you hear him a lot more around the team room and the gym now."
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