Depending on your needs, Hennessey Performance can upgrade a ZL1 from between 650hp to over 1,000hp.
John Hennessey and his team have been hard at work assembling a tuning program for the Chevy Camaro ZL1, and the results are as follows. Dubbed the HPE650, the tuned ZL1 features a 6.2-liter supercharged V8 equipped with a cold air induction system, stainless-steel headers and an upgraded intercooler. Hennessey also added new pulleys and revised the ECU. As a result of these mods, as well as fitting a new camshaft and high flow cylinder heads, engine output has increased significantly.
Specifically, the stock ZL1's output of 580hp and 556lb-ft of torque has been boosted to 658hp and 707lb-ft of torque. In addition to the HPE650, previously announced HPE800 and HPE1000 packages can also be ordered, which bump power to 800hp and 1,021hp respectively.