I auto-x with the H&R spacers (15mm) installed on all 4 corners, no problem at all with a good quality spacer with replacement studs.

The spacers make no performance loss and add stability and handling gain. Worth every penny, but I highly recommend the stud replacement versions from H&R (sourced from Josh @ Stillen) as they are inherently more secure being bolted thru the hub to the wheel. See the Stillen site for my DIY on spacer installs or check out my DIY posted in my sig.

im not sure... they dont weight that much to begin with. mine are Kic's 15mm with the hubcentric rings for the rear.

some stores sell these saying the hubcentric rings are recommended but not required... well, on our hubcentric wheels they ARE required. so if you're going to run anything smaller than 15, make sure you get the ones with the new studs and hubcentric rings built into the spacers. the 10mm Kics do not have the hubcentric lip.

The H&R are hubcentric and are made from billet aluminum. I didn't weight them but I take them on and off regularly when I switch wheels. I would guess roughly 1lb each depending on thickness.