this is a pic of the centre muffler... it also has a second cat converter built into the first 1/4 of it then the rest is a muffler thats why these cars are soo quiet when stock Could you tell me what you replaced this with and what you did with the sensor that goes into it. Thanks hi john. well for mine i replaced that centre muff/2nd cat with a small high flow muffler. sensor is between the first cat and the centre muff so dont even have to even go near the sensor. Hey Will but there is a sensor which goes into the centre one,where is that now?and did you have any warning lights come on cos i read about that somewhere here. The rear muffler is hollow too,unbolted from centre muffler and car sounded the same(quiet) my exhaust guy is doing some research on it.. He knows people B) Hi john, I dotn think there is a censor on the centre muff because there were no cables that were unplugged , unless the sensor uses wifi technology. Also no engine light because the o2 sensor is between both cats i know this becasue i was little worried about getting a light and asked the guy and he showed me where everything was. Also the rear muff is actually just a resonator. Mine has a sensor plugged into it.. Mine is 08 and that pic above is 07 and i cant see one, and i believe Will that yours is an 07 as well?Maybe something changed since then. Tomorrow i'll try get a pic of mine and hopefully shed some light on it.