Hennessey’s upgrades to the potent 6.2-liter V8 Tahoe and Suburban see the Texan team increase the power by more than 200 hp to 625 bhp @ 5,500 rpm, while torque grows by more than a third to 633 lb-ft @4,200 rpm. The significant performance enhancements make the GM models among the most formidable SUVs on the market.