i have a bit of light shudder. I also found the wheels bearings loosened up after bedding in and this caused heaps of shudder along with making the discs surface irregularities. A light skim sorted if out along with re-torqueing the discs. I have just picked up a pair of BMW 733i 4 pot calipers which I will be working on trying to fit to the EF Steering knuckles. Volvo seem to have nice alloy 4 pot calipers too but they run 2 lines which I decided was getting too complicated. This has been a long term plan to improve the brakes that is finally taking a huge step forward. I have a spare Steering knuckle and old set of discs so I can get it all worked out before trying to fit them up.