I have one, with a Linn Basik + tonearm, that I do not use any more, but I upgraded the platter with a SRM TECH acrylic platter, and it made some nice differences.
Highs got less splashy sounding than with the glass platter, and the midbass became more defined.
http://srm-tech.co.uk/epages/4c008923-2265-416e-a207-cc9dd8b06028.sf/en_GB/?ObjectPath=CategoriesI also upgraded the felt mat to better, generic mat I found on Ebay, for another small sonic upgrade. They can still be found there. Just search for Systendek upgrade mat.
You should also replace the sponge dampers in the springs with new ones. Some people claim that memory foam works great. I used foam designed for Linn Sondek. People on this sub-forum should have good recommendations.
One more easy upgrade, which I did, but I am not sure I noticed any differences, but it is so easy and cheap, it might be a no brainer. Cover the inside of bottom cover/plate with some Dynamat or similar type of sound deadening material. It is supposed to make a small difference in low bass. YMMV. It is supposed to make a bigger difference with the plastic bottom plater, than the metal one. My TT has the metal one, so maybe that's why I didn't notice a difference.
I keep remembering more upgrades. SRM TECH also has damping rings that go around the outer edge of the platter. They work on glass and acrylic platters. They create a wave trap to improve dampening and lower resonance. They also may improve rotational stability.