A stock LB7 can handle around 400 to 450 horsepower. However, this number will differ based on the condition of your engine and other factors such as transmission, clutch, and tires. If you're looking to increase the power of your LB7, there are a few things you can do. You can install a larger turbocharger, upgrade the injectors, or add a nitrous oxide system. With these modifications, you should be able to safely increase the power output of your engine to around 600 horsepower.