I had the front tensionser and guides put in at 50,000 miles, along with the manifold gasket upgrade. Since then no issues. This engine is one of the best tuned and relaible I have ever owned. Never had any timing chain stretching issues.
The 5r55e also gets a bad rap, but I have only had to change the EPC solenoid with new bracket, and I did that around 175k. No issues since.
I hope to go another year, before I get the itch for something fresh. Ive owned it since 1999, bought it with 30,000 miles on it.