if you need them, I am sure I can dig out my old rattler dampeners....

Thanks everyone for all the information! I've learned a ton.
Fixittt is going to set me up with some rattler dampeners. Cool guy!
I'll try that out and let everyone know how they work.

I would also recomend getting some thrust bearings for the motors if you dont have any already.  If you put thrust bearings inbetween the motors can and the screw coupler, and the motor can and the dampners it will keep the shaft from being able to move inside the motor can.  Which could result in backlash issues.  I know I had major problems with the xylotex 269 motors with massive amounts of shaft play inside the motor can.

im waiting to hear the results of the dampners

I only had a few moments between when the package arrived and when I left for Thanksgiving. On first try with one axis, it didn't seem to make much of a difference. When I get back I will experiment more.

dont forget to tune the motors again.  You should be able to notice a difference with the accel really low.  Jog an axis and listen to it ramp up.  Then put a dampner on and jog......

I've been experimenting some more. When I realized windows update was still enabled, I disabled it and got to 45 IPM without the dampeners. Using another faster PC, I'm up to >50 IPM. When I have some more time, I plan to see what the upper end is.