the GEM sleeved blocks are fine. the sinking issue has been completely resolved, and again that was maybe a handfull of blocks. it's not like the happend to 20 blocks out there but more like 4 or 5 MAX. dart is good for full race, but for street, the more open design of the gem is way better due to cooling issues. dart new sleeves are not much better than a block guard, as we all know about those causing heating issues.