It’s a strange business to be in, but around this time of year Universal Studios thrives in making its guests feel uneasy.

Make that downright scared.

Whereas Disney annually enchants guests by decorating Disneyland at Christmas, Halloween has turned into big biz for Universal’s theme park, with people shelling out more than $50 apiece to check out Halloween Horror Nights, which turns the park into a haunted house.

Last year, U sold more tickets to the event than it had in any previous year. And much as film studios strive to top themselves in sequels, producers of the fright fest — which runs 13 nights between Oct. 3-Nov. 1 — feel the pressure to turn up the scares as well.

“We keep pushing the limit,” says John Murdy, creative director at Universal Studios Hollywood. “As horror movies evolve and change, we feel we have to follow that trend. We’re the movie studio that invented horror movies. … We have to be more edgy than the horror movies out there.”

This year’s incarnation boasts a bigger budget and double the number of attractions and cast members.

The studio’s backlot tram tour, revamped as the “Terror Tram: The Nightmare Tour,” will be longer, unloading passengers at the Bates Motel from “Psycho” and guiding them through a series of mazes, as well as an altered version of the “War of the Worlds” plane crash set.

A new “Nightmare on Elm Street: Home Sweet Hell” maze re-creates the house that Freddy Krueger invades in the pics, as part of a licensing deal with New Line.

Other new mazes around the park include “Friday the 13th: Camp Blood,” “The Texas Chainsaw Massacre: Back in Business” and the “Universal House of Horrors.”

“It’s the most ambitious thing we’ve ever done,” Murdy says.

Naturally, the eventalso promotes U’s horror releases, with the tram screening footage from the upcoming remake of “The Wolf Man” and hosting a special “scare zone” featuring the masked characters from “The Strangers,” which hits DVD around Halloween.

While physical contact with guests is off-limits, organizers have plenty of other ways to scare them.

Physical effects include prodding visitors to walk through hanging underwear, fake carcasses or faux skin hanging from hooks or spraying them with liquids. This year it’s also piping in such gross odors as vomit, feces and rotting flesh.

“Every year, if there’s a line, we cross it,” Murdy says. “That’s how you touch people. Those things send triggers to your brain.”