In addition, with Jeeps like the XK you want usable power meaning low end. With a bigger cam youll lose low end but gain top end. Going with a 6.1 cam and valve train is in my opinion the best choice cause its really cheap- Most guys are upgrading their 6.1s- gives you a decent 35 hp and 30 ft lb or torque at usable ranges. Obviously if youre hitting the rev limiter in your XK constantly you may want a larger cam but Im assuming you are probably like me and like midrange tq. Also, you'll need to get an Intune and get the Jeep tuned properly. Make sure to have supporting mods done to increase cam effectiveness and save on tuning once.