Define improvement. Are you looking for more exhaust note, power or both? If you think of the engine as an air pump for a moment you can picture how flow out would be less restrictive, and therefore a small gain. But chasing performance is a balance game. Ideally you want to improve the intake and exhaust commensurately, then one might look at the various tuning software offerings to complement a freer breathing engine. If you're seeking a shove in the back improvement, you're likely to be disappointed, if you're looking to have fun, feel like a personal custom tuner and that's part of your Porsche ownership joy, you're all good. PS Exhaust changes can yield CEL dash warnings. IMO, the headers and sport cats will yield more than simply removing one cat.