'Cocaine Cowboys' filmmakers take us inside the making of their new Netflix docuseries - from the star witness reaching out on MySpace to getting Pitbull to rap the theme song

Simply known as "Sal and Willy" in the Magic City, the duo used their talents as powerboat-racing champions to traffic cocaine into the US — and in the process built a drug empire.

The wild ride ended with authorities indicting them in one of the largest drug cases in US history after the duo were accused of smuggling over 75 tons of cocaine into the US during the 1980s.

In the years they've been trying to tell the story of Sal and Willy, filmmakers Billy Corben and Alfred Spellman built a franchise telling other Miami drug tales with their popular documentary franchise, "Cocaine Cowboys" (comprised of 2006's "Cocaine Cowboys," "2008's "Cocaine Cowboys 2," and 2014's "Cocaine Cowboys: Reloaded").

Now, with the backing of Netflix, Corben and Spellman have finally told Sal and Willy's story with "Cocaine Cowboys: Kings of Miami."

Available now on the streaming giant, it's a thrilling and darkly funny six-episode journey into the heart of a Miami drug-running family.

Insider spoke to Corben and Spellman about how they gained the trust of the kingpins, reveal the importance of a deleted scene, explain how the FBI helped them out, and how they landed Pitbull for the series' theme song.

WARNING: Spoilers below if you haven't seen "Cocaine Cowboys: Kings of Miami."

Though the draw into watching "Kings of Miami" is learning more about the powerboat-racing kingpins Sal and Willy, once you are in it you realize that Sal's longtime girlfriend and bookkeeper Marilyn Bonachea is the real star of the docuseries.

Her riveting interviews showcase all the behind-the-scenes goodies of the rise and fall of Sal and Willy, which ends with her turning on the two as she agrees to be a witness for the prosecution when Sal and Willy are finally taken down.

Bonachea spent years in witness protection, and when she got out in the early 2000s she wanted to tell her side of the story. After seeing Corben and Spellman's "Cocaine Cowboys" in 2006, she knew she found her storytellers.

"Marilyn was basically fresh from witness protection at that point," Corben told Insider. "She had lost track with most of her family, including her parents who she didn't know if they were dead or alive. She had been alone for a long time."

So was there some covert way she contacted them? Nope.

"We got a MySpace message from Marilyn!" Corben revealed with a laugh. "That's how long ago this was. If you really want to date the project."

That began Corben and Spellman's journey collecting information for a Sal and Willy documentary. For years, the duo shot interviews on the side while making their other "Cocaine Cowboys" documentaries.

"We spent four days interviewing [Bonachea]," Spellman recalled, "and from there it was a matter of trying to find more people."

Like all their documentaries on drug cartels, Corben and Spellman don't just want to hear from the kingpin side but from law enforcement too.

The story of Sal and Willy was no different, and reaching out to the FBI for information on the case led to a major find.

The eventual fall of Sal and Willy was precipitated by the FBI obtaining Sal's ledger. Yes, he kept bookkeeping of not just the payroll of his drug empire but who he was paying off, which included police, judges, and politicians.

However, it was all in code — and that's where Bonachea became vital for the authorities. She was the one who wrote up everything in the ledger.

Thanks to the FBI's cooperation, Corben said they were given the ledger, which they hand to Bonachea on camera in an episode so she can reveal which people are related to specific code names in the book.

But Spellman couldn't believe what else was in the box of evidence the FBI loaned to them.

"Along with the ledger, there was this furry thing at the bottom of the box," he said. "I was like, 'What the hell is this?' We pulled it out and it was the wig Sal was wearing when he got arrested in 1997 in the Ritz Carlton in Palm Beach."

Opening every episode of "Kings of Miami" is the catchy theme song written and performed by Pitbull, called "Blood Sport."

Having the Miami artist involved in the project was a major highlight for the Miami-based filmmakers. But it turns out "Mr. Worldwide" recorded the track years ago when telling the story of Sal and Willy was still just a pipe dream.

Corben wanted to do a hip-hop soundtrack to accompany the release of 2014's "Cocaine Cowboys: Reloaded," which featured footage and interviews that didn't make it into the 2006 doc.

The movie's composer put together some tracks with music similar to the score and then Corben and Spellman sent it out to Miami-based rappers who in the past were supporters of "Cocaine Cowboys," asking if they would add their raps to it.

"Pitbull was the only artist to send something back," Corben said.

Though the "Cocaine Cowboys" hip-hop soundtrack idea was scrapped, the filmmakers held onto Pitbull's "Blood Sport" track. And when "Kings of Miami" became a reality, it became the docuseries' theme song.

"I thought the song was brilliant," Corben said. "It's all from the perspective of cocaine. He takes over the voice of cocaine and talks about it in the first person, which I thought was very clever."

One lyric in the song Pitbull raps goes: "They'll kick in your door like Bruce Lee / just to have an intimate love affair with me / I corrupt governments / yeah that's me / I built the streets / listen closely."

The filmmakers said they don't know if Pitbull has watched the series as he's currently on tour, but they are trying to get his theme song released on Spotify and iTunes.

Watching "Kings of Miami," it's clear that Bonachea and Sal were already on the outs when she surprisingly agreed to take on his elaborate drug bookkeeping. So, why did she suddenly want to help him?

It turns out a deleted scene that the filmmakers say Netflix will soon release on its YouTube channel will bring some clarity to this.

"They were out of touch for three years until her brother got arrested in a double homicide," Corben explained of how Bonachea and Sal started speaking again.

In desperate need of a lawyer, Bonachea turned to Sal for help — though she was very reluctant to ask him for assistance.

"She knew it was like 'The Godfather,' she's going to have to owe Sal a favor," Corben said.

Sal helped Bonachea's brother get a good lawyer, who successfully argued for a life sentence instead of the death penalty. But Sal wasn't through with Bonachea after that.

"Sal started giving Marilyn $5,000 a month to help in the trial and that's what led to Sal asking her to start helping out with the ledger in the 1990s," Corben said.

Corben said though this was an important part to the story, the sequence was cut for time.

Telling the story of Sal and Willy is the culmination of decades of work by Corben and Spellman and a little luck.

The filmmakers say after Sal read a story about how they wanted to make a documentary on him, the former drug kingpin reached out to them from prison and allowed them to use old photos and even gave them entry into a storage space filled with information from his trials.

It's the most ambitious chapter in their "Cocaine Cowboys" franchise, and it sounds like it won't be the last the filmmakers tell.

Corben was a little late getting on the interview with Insider. But he had a good excuse, as he revealed when he got on the phone: "I was on the other line with someone from the Mexican drug cartel who saw the show and now wants us to make a documentary about them," he said.

Like Bonachea's call years ago led Corben and Spellman into the Sal and Willy story, it looks like the duo could be setting forth on a new drug tale.