Since Fall Out Boy came back swinging this April with Save Rock and Roll, they've been more than a little busy (see above: Pete Wentz's travel delirium). Two separate tours had them zigzagging across America, and yet, they still had time to make a new EP with Ryan Adams on production duties, titled Pax-Am Days. The eight-song, '80s/'90s-influenced EP comes out October 15 on Island Records, along with a double disc reissue of Save Rock and Roll, but it's streaming exclusively on KROQ (a Radio.com station) right now until its release.

When asked why they focused in on '80s and '90s metal and punk with Pax-Am Days, Wentz's answer was simple: say what you will about their pop sheen, but Fall Out Boy grew up on that heavier kind of music. He named Metallica's Master of Puppets as one of his "single biggest influence" and shouted-out Gorilla Biscuits, Los Crudos, Damnation A.D., The Descendants, Screeching Weasel, and Earth Crisis, who was "crucial" to the development of Wentz's own persona.

"That's the music that got us into playing as Fall Out Boy and we wanted to pay homage to that," Wentz continued. "I think, for bands like us, we can be a gateway. We can say like, 'Hey, check out what these other bands we grew up with do.' I think that's an important thing to do as an artist. But most importantly, it was just kind of exercise in fun. It was like, 'Let's just make noise and if it gets recorded, cool; if it never comes out, cool.' And that's something that we decided last time around, that this was going to be something that was really important to the future of Fall Out Boy. It was just kind of to make sure we were always having fun in the process."

Working with Adams helped the band keep things fun and not over-think. "It was wild," Wentz said. "Ryan's brain works in such a divergent way. One minute he's telling a joke about kale salad and the next minute we're talking about old punk rock. I think that in some way it's childlike wonder, and in some ways it's so genius and different. He's such an outside-of-the-box thinker � it was really good for our band."

That theme of childlike wonder permeates everything Fall Out Boy is doing right now. Wentz describes the band as being in their teenage years, at the point where they can "make some noise and wreak some havoc"�but still spare their hearts and livers a little. "We're probably at the stage where we get acne and stuff�or the band does," Wentz joked.

The guys will channel the youthful energy into a charitable cause later this fall: they'll play a November 29th benefit show for the GRAMMY Foundation with money going toward music education. Wentz himself describes his music education happening in a "bizarre way."