Pyro is late. Ryu is unfazed.

"He's on his way," says Ryu. "He'll be here in a minute."

"Pyro" isn't a government name (duh). Neither is "Ryu." Both men are now approaching their mid-twenties, and the further away they get from their teenage days, the further away they get from using anything but their aliases to identify themselves.

Pyro and Ryu form a music-production duo called Sound M.O.B. They've existed as such for nearly the last decade, mostly as local guys accomplishing admirably local things. Currently, though, their song "Drank in My Cup," a saucy, hypersexy, catchy aggregate of mechanized thumps and machismo that rapper Kirko Bangz has dry-humped to national fame, is being played to no end across the country. And they're feeling pretty good about that.

Ryu is sitting inside a homemade studio attached to his parents' home in north Houston. Outside, a man with no shirt pushes a lawn mower down the middle of the road.

Tim Seriki, part of the group's management team, opens the door. He's there to film the recording session for a documentary being shot about Sound M.O.B.

"Where's Pyro?" he asks.

"He's on his way," says Ryu. "He'll be here in a minute."

Pyro and Ryu met in high school through a mutual acquaintance, a local rapper named Krucial who now operates as one of the house rappers under the Sound M.O.B. umbrella. The three other acts are another rapper, Cool i10 Jones, and R&B artists Prince Cannon and Ashley Williams. Sound M.O.B. is trying to grow a brand.

Pyro walks in.

He and Ryu are different in obvious ways. Ryu is Latino, Pyro is black. Ryu's family has a musical legacy that extends back at least three generations, rooted firmly in Tejano (Ryu actually plays the accordion); Pyro is the first of his to pursue music. But the two are alike in the most important way.

"When I met Ryu, I knew that he wanted to be in music as badly as I did," says Pyro. "We'd go in the studio from 5 p.m. until 7 a.m. and just vibe."

"We were working one time and got so into it that my truck got stolen from right outside while we were right there," remembers Ryu. "We never even noticed."

Slowly, after the hours added up to a marketable skill set — Pyro literally started making beats on a PlayStation console as a child — the twosome earned a reputation, creating auspicious, warbly, Southern-friendly rap sounds that eventually attracted the attention of Houston stars Slim Thug, Killa Kyleon, Chamillionaire and more.

Sound M.O.B.'s power grew, and they began stacking accomplishments to run parallel with their catalog of beats.

In 2008, they won the Houston division of Red Bull's Big Tune producer battle, crushing local contemporaries. They were flown out to New York to compete in the national finals.

"We got no love," remembers Ryu. "We were heavy on our Houston shit back then. They weren't feeling it. It sucked. It taught us to learn to incorporate new sounds."

Another time, a song of theirs was supposed to have landed on the 2009 collaborative album We Are Young Money, on Lil Wayne's Young Money label. The project eventually sold more than 500,000 copies, but Sound M.O.B.'s contribution ultimately fell through without any warning.

"We got a call from [musician] Pleasure P, who was touring with Wayne and them," says Pyro, head nodding side to side as he collects his words for the rest of the story. "He was like, 'Ay, we just recorded a song on the [tour] bus to your beat. It's gonna be on the album. Wayne, Drake, Nicki [Minaj] are all on it. Someone'll be calling you.' We were so live."

"I remember checking my phone every day," says Ryu, pantomiming picking up a cell phone and checking its home screen.

"I'd look all day," he adds with a laugh. "They didn't call for three months."

"After they called, we thought we were on there," Pyro recalls. "We sent them the files, filled out the paperwork. We were online every day looking for track listings. We saw it on Wikipedia and it had our song title but different producers. You know, Wikipedia you can go in there and edit, so I was like..."

He continues, pretending to type on a computer, posture exaggerated for effect. Everyone in the room is smiling.

"I went in like, 'You got the wrong producers; we made that,' and changed it," continues Pyro. "When it finally came out, the title was the one that we were told was ours, but it was someone else's beat."

Heartbroken?

"That ain't the word," says Pyro. "It was hard."

The lesson there: Production can be a real bitch sometimes.

From there, though, things moved upward. Quickly.

Sound M.O.B. secured a bonus track on Bun B's 2010 album, Trill OG, then walked backward into producing Kirko Bangz's first radio hit, the robosexual "What Yo' Name Iz."

After Michael "5000" Watts broke the single on his Sunday-night 97.9 The Box show, it spread swiftly. Labels came looking for Bangz, and after he signed a deal with Warner Bros., they wanted more music. So the rapper went back to The Mob.

"He [Bangz] came in one night and said, 'Man, I need a single,'" says Pyro. "The label had this real pop radio-like song ready for him to release, and he wanted something else. So he just came in and said to give him a hit. We worked all through the night."

Ryu cues up the actual beat from that night.

"It was almost exactly one year ago that we made it," Ryu says.

He clicks it on. The swooping WHOOOOMMPs that announce the beat's presence fill the room as rapidly and unforgivably as they do any club or concert venue. All these months later, "Drank in My Cup" still sounds special.

It is the first song of the budding new generation of local rappers to truly gain any national traction, and will eventually be remembered as a flagship moment, for certain.

"When Kirko heard it," reflects Pyro, "something just clicked. I don't know if he had the lyrics ready or what, but he just started going."

He begins singing the hook.

When The Box debuted it in July 2010, the morning crew was so swayed by its immediate appeal that they played it again as soon as it was over. And when it was over the second time, they played it a third. Each time it drew more and more praise.

Everyone knew it was going to be big. And now it is. This spring, "Drank in My Cup" reached the No. 1 spots on Billboard's Rhythmic chart and Billboard's Rap Songs chart. It's the first time a song from a Houston rapper has been that high since Chamillionaire's paradigm-shifting "Ridin' Dirty" in 2006. And it stayed at the top for several weeks, higher than perennial world-beaters Flo Rida, Drake, Rihanna, Young Jeezy, Kanye and more.

So now what?

"That's where we are," says Ryu. "We're lucky that we're in a position now where these record labels are trying to sign us now. They've seen that we can make hits. We want to be real careful, though. We don't want to rush into anything. We want to make it, but it has to be right."

In other words, they're on their way. They'll be there in a minute.