Banks Power Derringer Tuner (66652)
Fits 2017-2019 6.6L Duramax V8 (L5P)

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The Derringer is a small module that wires in and talks to the factory engine computer through the OBD-II port to raise power. It does not reflash or permanently rewrite the ECM.
why this one — The L5P's factory ECM is locked from the factory, so unlike LB7 through LML trucks you cannot just load a custom tune file onto it. The Derringer works around that by signaling the stock ECM instead of rewriting it, which is exactly why Banks can rate it 50-state compliant under designation D-161-149 while still claiming plus 61 hp and 112 lb-ft. Two things to know before you buy: this part number is the tuner only, so you need a Banks iDash SuperGauge or DataMonster separately to change levels, and despite being called plug-and-play, Banks own install estimate is 3 hours because the harness routes into the engine bay.
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