Suboxone (Buprenorphine) has a half-life on average of 37 hours. So it'll be completely out of your system in about, oh, 24 days.
30 days @ 8 mg day = 32 mg total in system.
32 mg/37 hrs=576hrs for .000122 mg in system
576 hours /24 hrs = 24 days.
I might not always be right, but I'm never wrong.