AUSTIN, Texas – “Harold & Kumar Go to White Castle” didn’t exactly do gangbusters at the box office when it opened in July 2004. The comedy about stoner pals with major munchies searching for tiny hamburgers in the middle of the night made about $5.5 million its first weekend on the way to an $18.2 million gross domestically.

But the film’s writers, Jon Hurwitz and Hayden Schlossberg, always had faith that it would find a following eventually through DVD rentals and cable-TV viewings. And now, their faith has been rewarded.

The sequel “Harold & Kumar Escape From Guantanamo Bay” premiered at the South by Southwest film festival over the weekend to a raucous, packed house. (The movie, which also marks Hurwitz and Schlossberg’s directing debut, opens in theaters April 25.)

This time, Harold (John Cho) and Kumar (Kal Penn) are suspected of being terrorists after Kumar sneaks a high-tech bong onto a flight to Amsterdam, which everyone onboard thinks is a bomb. The two get sent to Gitmo but manage to break free, ending up in Miami and Texas and – of course – running into Neil Patrick Harris playing a mushroom-eating, hooker-loving, unicorn-riding version of himself.

“When we were in college we liked cult movies like ‘Dazed and Confused’ and ‘Office Space’ and ‘The Big Lebowski,’ and these were movies that weren’t huge box-office smashes but sort of found an audience on DVD the year or two after the movie came out,” Schlossberg, 29, told The Associated Press. “We felt with ‘Harold and Kumar’ when it came out in theaters in 2004 that if people saw the box office, it wasn’t going to end there.”

Cho, who’s also appeared in the “American Pie” movies and plays Sulu in next summer’s “Star Trek,” said he’s sensed a real clamor for more among the fans who’ve given the first “Harold & Kumar” a cult following – and that can be a little overwhelming.

“I’ve wanted to satiate them, really. Being unable to has been frustrating. I’m glad it’s coming out now – I just hope people like it as much as they did (at the premiere),” he said. “People are insanely enthusiastic. People forget that I don’t know them, though they may know me, so they will yell at really piercing volumes at times – like, 3 feet from me and my wife – and it’s scary. But it’s great, and it’s loving.”

Although “White Castle” was only their first produced script, Hurwitz and Schlossberg always knew they wanted to do a sequel, and they knew they wanted it to pick up immediately where the first one left off as their favorite ’80s sequels always did. Initially, they’d planned to have the pals travel to Amsterdam to find Harold’s crush, Maria, but they didn’t want a movie where the two just traipsed around Europe the whole time.

“Then we started thinking about Kumar getting into trouble on the airplane, some racial profiling, Homeland Security getting involved, then Guantanamo Bay, and suddenly all these ideas just come out,” Schlossberg said. “It wasn’t a conscious effort to make something more political. It was really just: ‘OK, how can we amp it up a notch?’ And the first movie, our story was so simple. I mean, there were no stakes whatsoever. So in this movie, for us the joke was, let’s give almost the exact opposite – the highest stakes of all time. Let’s have literally Homeland Security chasing after them, it’s a national security threat, their lives are at stake, their freedom is at stake.”

“One of the things that people really enjoyed about the first film was that second layer that’s saying a little something, a little bit of social relevance,” the 30-year-old Hurwitz added, referring to the original movie’s ethnic humor. “While coming up with the story of the sequel, it was important to us to find that second layer. We love a good (poop) joke as much as the next guy, but there are a lot of bad (poop) jokes, and we feel like really sophomoric comedy works best when there’s something smarter going on, and vice versa.”

Penn, meanwhile, views both primarily as buddy comedies.

“The first one was talked about as being a movie about weed and this one is being talked about as being a political movie. I don’t think that’s the case in either film,” said the co-star of TV’s “House.” ”I think it’s a movie about two friends and the journey they go on. And in the first case, getting food in the middle of the night was what brought them closer together. And in this case, struggling for their freedom is what brings them closer together.”

Friends themselves since high school, Hurwitz and Schlossberg also amped up the stakes by directing for the first time. “White Castle” director Danny Leiner wasn’t available for the sequel, and rather than choosing some random person who didn’t know the material, they wanted to give it a shot.

“It’s being naive that helps. We weren’t worried at all,” Hurwitz said. “We were on set the whole time for the first ‘Harold & Kumar’ and we had a great working relationship with Danny Leiner on that first film. And just sort of shadowing him and standing behind him as he directed the first film, giving our input throughout the movie and throughout the (post-production) process, we felt very included.

“A lot of times, writers get very tossed aside right away,” he added, “and we were kept in the family on that first movie, which allowed us to learn a lot.”

“If we had more experience, we would have been like, ‘We need more time, we need more money, we need more everything,'” said Schlossberg. “But because we didn’t know, we were just like, ‘Thanks.'”