I had my guibo changed as it was cracked and I was getting a very heard to perceive vibration/sound over the center, felt best by holding the stick. After, it is less noticeable but still there. I notice under load, being speed sensitive a slight thumping heard mostly under heavy load or acceleration. This is best heard in 3rd or 4th near 2000 rpm. When reving the engine in neutral I get nothing but turbine smoothness. I have about 90k on the car. I haven't had the tranny mounts or center bearing changed. Has anyone had to go and balance their stock driveshaft? I'm not overly worried but curious if there are any easy suggestions to improve this.