A couple of years back I had a hyper single clutch fitted by a specialist and ever since I've had a vibration off throttle between 3500-3000 rpm. Anyway I don't believe it's a quirk of the clutch as it's been fitted to others and there haven't been reports of this problem, plus the fact that the gearbox is still fine and performs well, as does the diff. Anyway, seeing as the clutch was the only thing drivetrain related that was changed I'm starting to wonder whether the prop shaft was rotated at the centre joint and wondered if my symptoms would likely be caused by this? The only other thing I can think of (but it's with a limited understanding of exactly what it does) is whether the spigot isn't located properly? If I was to rotate the joint to see if it gets any better, is there a danger from doing so? Cheers in advance for any info