And then there were four: Singers Suzie McNeil, Mig Ayesa, J.D. Fortune and Marty Casey are the last vocalists belting it out on Rock Star: INXS. Who'll walk away the new lead singer of the multiplatinum-selling Aussie rock group? PEOPLE caught up with the quartet about lessons learned – and got the scoop from INXS lead guitarist Tim Farriss on what each rocker has going for (and against) them.

Rock Star: INXS: The Final Four| INXS, Rock Star: INXS

Marty Casey

Age: 31
Hometown: Chicago
Best INXS advice: "The first thing (INXS) told me was, 'Calm down,' " says Casey. "At first, they called me a screamer and not a singer. I started just singing and being sensitive with the vocal."
Bonding with the competition: Several of the singers got inked together. "(Former contestant Jordis Unga and I) got the same tattoo. It's a small ring behind the left ear – it's a portal to creativity and the left side of our brain," says Casey. "Suzie got a ring around her arm and J.D. got the number 448, which is his number of fate."
Marty's pros and cons: "He's such a better performer and singer in every way than when he started this competition," says INXS guitarist Tim Farriss of Casey. "But Marty spent a lot of time in previous years screaming, basically, and it's kind of annihilated a certain part of his voice."

Rock Star: INXS: The Final Four| INXS, Rock Star: INXS

J.D. Fortune

Age: 32
Hometown: Oakville, Ontario
Best INXS advice: "To just relax and sing the song," says Fortune. "I've developed more eye contact with the audience and less of a need to be all over the stage."
Bonding with the competition: "I've changed my attitude to the point that I'm not on attack mode with the other contestants," says Fortune.
J.D.'s pros and cons: "He definitely has that 'X' factor, that star quality. When he walks into a room, you say, 'Wow, who's this guy?' " says Farriss. "But he hasn't got the strongest voice in the world, and he knows it."

Rock Star: INXS: The Final Four| INXS, Rock Star: INXS

Suzie McNeil

Age: 28
Hometown: Toronto
Best INXS advice: "Not making it showy but getting into the lyrics and getting into the depth of the song," says McNeil. "There was talk of my smiling too much when the song didn't call for it."
Bonding with the competition: "We have a date in Vegas where all of us are going to meet up again without any cameras or the pressures of the competition," says McNeil. "We're just going to enjoy each other for a weekend."
Suzie's pros and cons: "Of all the singers left, I think she's got by far the strongest voice – and she's a fun person to hang out with," says Farriss. "The question we have is does she have that 'X' factor, that 'rock star' quality that we're looking for? I don't know."

Rock Star: INXS: The Final Four| INXS, Rock Star: INXS

Mig Ayesa

Age: 35
Hometown: Sydney, Australia
Best INXS advice: Telling him to stop singing so nasally. "It's the comment that is making me work harder than anything else that's been said," says Ayesa. "I sing way too high for my own good, and the only way I can sing that high is by squeezing my butt cheeks!"
Bonding with the competition: "You go through every gamut of emotion you can possibly imagine together – living, working, stressing out," says Ayesa. "When someone leaves, it's really heartbreaking."
Mig's pros and cons: "Mig has a great voice. He's obviously a talented piano player, he's one of the nicest people you will ever meet. He's Australian, too, so he's got that going for him!," says Farriss. But, his theatricality could work against him. "Some of the guys (in INXS) still feel he's got a lot of (musical) theater in him."