Rear pivot block
 

on the xxx-cr Ive read in the setups a bit about flipping the rear pivot block, but do people recomend it?? advantages / disadvantages ?

cheers

we have tryed it both ways and at a variety of angles
we prefer right way up and use 0 degree block on most tracks

The reason for this is it raises the hingepin height and allows the car to go through the bumps better.
If you do this mod you need to sand the small lugs off the top so it is flush, flip it over and score where the outdrives are, and dremel/file enough material away so the outdrives don't catch on the block (don't worry if you expose the hingepins when filing away as this is fine).
The best pivot support to use is the stock 2deg one.