Need a Barton bracket or some sort of aftermarket shifter. I don't have a boss mani but I had this issue stock. Also my clutch peddle sucks to the flow at high rpms. Took out the assist spring, changed the fluid to dot 4, and bought/installed a Barton shifter. Clutch feel still kind of sux but it was a drastic improvement over stock.
2013 5.0 m6 base 3.31's tint 20in Shelby razors 255/35/20 falken fk 452's koni srt.t's sr springs j&m phb gt500 mounts upr rear billet lower ca's upr brackets upr adjustable upper ca flowmaster at classics steeda cat deletes airaid cai premium st brace jlt catch can MGW shifter and blk ball. Currently bama tuned 400hp 383tq. Zex blackout kit w/msd digital window switch, fpss, zex bottle heater, bottle opener, blow down, and purge with a dyno tune coming soon..