But for the 30 minutes it took to install, and the $1,200 it cost, you’ve done what GM engineers wanted to do before the lawyers stopped them. You’ve let the L5P breathe.

You take it on the highway. The 98-mph governor is dead. You pass a semi at 110 mph with 40% pedal left. The EGTs are lower because the timing is advanced. The regen frequency? You’ll forget it exists until the "Cleaning Exhaust Filter" message pops up 800 miles later.

The Prelude