From personal experience, Id leave the shafts in if I can. My interior is vibrated to hell, alternator and powersteering pump have jumped off the motor multiple times...people ask me "is the car supposed to shake like that?!?!?" Its just annoying...lol. The way I see it, you could possibly lose power by taking them out. Ever used an impact gun? Know when you got a loose grip on it and the gun just vibrates around? Then when you give it a firm grip, the gun stabilizes and can transmit more torque to the bolt...