The Timberfakes — Boston’s own Justin Timberlake cover band — were elated when the pop star announced that he’d be making new music. After all, the group’s set list had been a bit stunted with his hiatus. (It’s been a lot of “Sexy/Back” and “Senorita.”) But the release of Timberlake’s single, “Suit & Tie,” also meant that the band had to do some quick arranging before its day-after-Valentine’s Day show at the Hard Rock Cafe. The musicians were particularly perplexed about the harp sounds in the new song. Harps are not so easy to lug to the club. “That was a bit of a curveball for the band when we listened to the track together for the first time. There were a lot of discussions about who could cover what sounds and we left it up to our guitarist and keyboardist to come up with the arrangement,” ’Fakes singer Ryan Kelley told us via e-mail. Kelley also said he’ll have some help with that “Suit & Tie” falsetto. “We added a permanent female vocalist over the last year, who has been able to take on a lot more of the falsetto in the choruses for songs like ‘What Goes Around . . . Comes Around’ and ‘Cry Me a River.’ She’s amazing.” We were going to ask what Kelley plans to wear during the Friday show, but, based on the title of the new single, the uniform seems obvious.