Why would the plastic in the timing assembly be such a concern for wear?
Unless there are huge alignment issues, the chain will not be wearing out any of the plastic. If it is wearing it out, you would have catastrophic problems to worry about, never mind the plastic. lol
2009 A/W E93 335i-SOLD
2010 A/W E60 535i- SOLD
2008 E60 M5 MT - FLOODED
2013 M3 MT - AW/FR - Eisenmann Race
1991 Turbo Miata and 2013 Wrangler