In 2014, Mississippi rap duo Rae Sremmurd became hugely popular off the strength of oddball party anthems like “No Flex Zone” and “No Type.” The following year’s full-length SremmLife made good on those joyous pop-rap instincts; carried by the outlandish, even cartoonish voices of of brothers Swae Lee and Slim Jxmmi, they made joyous inclusive rap that produced enough energy to power a city block. Their music was fun, infectious, whimsical, and a potent (if momentary) remedy for agoraphobia.

And yet some rap fans cried “foul,” dismissed them as empty-calories frat-rap, a mix of LMFAO’s party rock cut with Ying Yang Twins crunk and packaged in the youthful exuberance of Kris Kross. When Complex named SremmLife its third-best album of 2015, former Hot 97 program director and current Beats 1 DJ Ebro Darden launched an all-out assault on the duo, saying that the selection couldn’t be valid. He accused the brothers of not writing their own raps and capped his comments with another diminishing jab: “It was a fabricated thing we all liked.” Two of the most electric new voices in rap were suddenly being reduced to the rap equivalent of Milli Vanilli. Mike WiLL Made-It, the super producer who helped mastermind the duo’s success (and the alleged ghostwriter), addressed the allegations on Twitter as only he can: “See the Problem is niggas be stuck in these old ass boxes they scared to jump out of…”

Jumping out of the box is exactly what SremmLife 2 does. Whether by design, by accident, or simply out of necessity, SremmLife 2 deconstructs the party-rap formula the duo perfected on their debut, zigging and zagging from Drake-esque rap-sung half-ballads (“Now That I Know”) to Mustard’s “ratchet music” (“Set the Roof,” with a Lil Jon-feature nod to crunk) to sugary bubblegum rap (“Just Like Us”), all while maintaining the spirit at the core of SremmLife. The album’s default setting is synthpop, retrofitted with Mike WiLL’s disorienting array of bells, whistles, tones, and clattering drum kits. Its most ambitious outings, like the back-to-back combo of metallic stargazers “Look Alive” and “Black Beatles,” push their talents to new heights by redefining what the duo can and will do. The songs hook into each other at the ends, creating seamless album-friendly transitions.

The weirdest and wildest moments on SremmLife 2 are its lifeblood. The album is stranger, artsier, and flat-out ballsier than its predecessor, especially considering the stakes (SremmLife produced five platinum singles; this is a follow-up that doesn’t seem to care much about that.) It’s a less dance-friendly alternative driven by the yelps and whines of its two stars. Slim Jxmmi tears through the hook and verse on “Start a Party” like a man possessed, moving at a ferocious pace that makes his voice crack. On “Swang,” which strobes in a fluorescent neon glow, Swae Lee floats in and out of a wispy falsetto. The most challenging song is “Take It or Leave It,” with Swae Lee going full crooner, belting out a pitchy-but-charming melody. When Swae jumps too far out of pocket, Jxmmi is there with the answer, settling things with even-keeled verses.

Swae Lee, in particular, is venturing into Young Thug territory: His arsenal of yips, squeals, and whistling falsettos has grown exponentially, and he’s willing to try just about anything now, which results in some strangely liberating artistic choices. But it’s Slim Jxmmi who really grows here. Many past Rae Sremmurd songs were exhibitions for Swae’s vocal acrobatics (“No Type,” in particular), with Jxmmi playing springboard, but Jxmmi is showing greater range and rapping with much more force. He even puts together some of the most quotable bars: “A young nigga so superb/I’m Kool Herc on the herb” on “Real Chill;” on “Over Here,” “Charlie Sheen is my clone/Can they fuck with us? No/Red carpets my home/VIP my throne.” Together they’ve become one of rap’s most exciting tag-teams, and it appears that the brothers are getting the last laugh on those ghostwriting allegations.

Rae Sremmurd were born of the “Crank Dat” and “ringtone rap” eras, where hooks and dances powered entire careers. That era of rap was often considered disposable, too. (Nas made a whole album about it.) But acts like Soulja Boy and Travis Porter have proven durable, and they’ve had a discernable influence on the Brown brothers, not just in their sound but their swagger: the sense of being unbothered, unburdened, and invincible that comes with being super-young, rich, and black. It’s that same sense of liberation that fuels the boldest decisions on this album. SremmLife 2 collects all of the quirks in the margins of its predecessor and develops them; more than anything else, SremmLife 2 is the ultimate middle finger to grouches who think this brand of rap can’t be complex.