The chain won't get to metal on metal with the metal guides.....
The metal guides are covered with a nylon where the chain rubs against them.
Even if you get to metal on metal, it's better than no guide at all (which is what happens with the plastic)
My OEM single row/plastic set lasted 99000 miles (changed because of rattle (due to guide breakage))
My aftermarket lasted 46000 miles (changed because it skipped 2 teeth (due to guide breakage))
At which point I went with the LC double row conversion kit.
