I don't think you'd need it bro(unless you go more for the look),10 years ago seems most everybody went with underbracing 'cause that was the thing at the time.I see a lot of bikes now without it,even big hp Pro Street and grudge bikes.Friend has an 18" over chromoly Evil arm(with no underbracing)on his all motor 1507 with a flat slick and with 250+ passes hasn't had any issues.