How important are spacers?

kenchan

i stay away from no-brand ones as there is no way to tell what kind of materials they used (sure they say watever they want, but how pure is it?), how was it treated to get to the strength expected?

what tests were conducted to validate them to be at oem standards, etc... i rather just spend a little extra for higher quality. i run kics, h&r, eibach. ichiba's have been okay for me but their craftsmanship is kinda crap.