My bike is a 2015 103ci Fatboy with a stage 1 kit.

Is a catalytic converter really detrimental to power in a base, say stage 1 kit, if so how? These days they have very little restriction.

How do they supposedly make the engine run hotter? My tests with slip-ons with and without catalytic converters, S&S turbo and Screaming Eagle mufflers, show no difference in oil temperature.

Any constructive comments would be greatly appreciated