BY J.S. HANSEN
The introduction of the Variable Vane Turbocharger (VVT) on the LLY GM Duramax in 2004 may have been mostly emissions-control related, but in the years since, it has proven to be a solid performer with great power potential—with a few tweaks from the aftermarket. The Garrett VVT used on the 2004.5-2016 Duramax has gone through a few revisions with each engine platform, but it remains a pretty solid turbocharger for daily driving, towing, and power output up to around 530 horsepower.