Well done. You do realise that police do troll internet car forums for stupid things like this.So saying they don't have a clue is a croc, you've just admitted to doing that, hope you get caught. They have these things for a reason, modern day cats are extremely efficient as has been mentioned, especially on the sportivo. iit was just a question... well... if i get extractors should i keep the current stock one ? to gain more power the one needs to burn fuel quicker more quickly, thus getting it in and out quicker, the most obvious way is to reduce restrictions in the exhaust and inlet. cat converters have alot of restrictions particularly stock ones. This is why 100% of track and race cars dont run with a cat converter as they are not required to have one and it reduces power, however this is illegal on a road registered car as pointed out by these tossers. yet its your car and opinions from pu55ys like these shouldnt deter you. i've worked on many track and racing cars and they have all ran a cat converter. where in this qoute do yu see wether he wants to use it on the street, is worried about cops and epa?? no offence intended for anyone but for all we know, hes planning on dragging or tracking his car. the point is, less restrictions = higher flow = more power.. which is nothing to do with police and epa and website patrol police.. answer dugongs question properly.. or dont.. why would you drag race a corolla??? obviously its for the street