The SRT 6.1 Hemi is a hand-built, balanced and blueprinted V8 with 425 hp in stock trim. It looks tight in the JK engine compartment but really is hardly wider than the stock 3.8 six it replaced. It's just longer. The big Howe aluminum radiator fits fine and, with the factory fan and shroud, keeps the 6.1 cool no matter what the outside temperatures are. We used Optima YellowTop batteries in both Wranglers.