First of all, you cannot remove the cat in any U.S. state which has emissions testing requirement and I believe that’s a majority of them, nowadays . You will not be able to renew your registration without passing a smog test
Secondly, even people who bought aftermarket catback systems ( for exhaust sound improvement and some weight savings ) with pipes LARGER than 2.5” have ended up with a more pronounced low end torque loss because of the back pressure compromise . This engine’s pulses are very finicky and lack of the exact Porsche-engineered back pressure has an adverse effect .. granted, it’s not a whole lot ( about 15 ft/lbs ) and only within a 300 or so rpm segment but around 3200 to 3500 rpm which is where most people drive / cruise at, so if you step on the gas at that level ,and don’t downshift you’ll get a flat spot you won’t like ..
Not sure what eliminating the cat would do ( where you could do that .. ROW countries perhaps , or here if you just plan to track the car and not drive it on the street ) , but the more back pressure you remove the greater the torque loss . If this car had a V8 , it wouldn’t be an issue.. actually I don’t know why the heck they didn’t do that ; the engine bay is big enough for a small block 8-banger .. Yeah, yeah, it would have thrown off our near perfect 50-50 weight balance, and the gas mileage would be poor , blah blah blah
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