The Fleece Performance CP3K is a modified Duramax LBZ CP3 designed to eliminate the factory fuel flow restriction that begins at 3,000 RPM. If you have a stock CP3 pump you are losing fuel flow and rail pressure after 3000 RPM, which correlates to lost ho Every Fleece Performance CP3 is tested on our in-house engine simulator and pump test stand to simulate real world situations and ensure that each pump is ready to work for you! Designed to eliminate the factory fuel flow restriction that begins at 3000 RPM;Correlates to lost horsepower when you need it most;Cost effective upgrade;Fuel pressure regulator will need to be scaled appropriately when installed in a 2001-2005 (LB7 or L