Boxer wrote:As I already stated - its not unsual or unexpected to get a CEL (some will, some wont). Its purely the ECU monitoring how efficent the Cat is by taking a sniff both before and after the cat/s and comparing the values. If the difference between these measurements is outside the expected range then the CEL illuminates along with cruise light flashing. The error code points towards "catalytic efficiency outside acceptable range".
Its no biggie and wont trigger 'safe mode' etc. The reason manufacturers make it look more daunting these days with cruise light flashing etc is because historically many owners we blase' about CEL's if the car still seemed to be running ok. This way owners pay more attention and get it looked at.
A high flow cat in many cases will not operate the same way as the factory cat and therefore the measurements are different to a stock system.
A tuner will simply adjust the thresholds in the ECU for the "acceptable range" and the CEL wont light unless there is a real problem.
UrbanGTB - The hose from the intercooler to the throttle-body is a common one not to be re-connected correctly and is a b@stard to get to. Others could be the two lines to the blow off valve. Most others wont need to be touched to fit the dump.
X2 for the lot including the TMIC pipe done that myself a few times
. I know with the Euro jobbies even the type of cat used can throw it out, whether it be 100 cel 200 cel 400 cel etc in some cases you need two cheap cats to equal one good one just to satisfy the ECU, as Boxer has indicated
Its best to get a tune anyway and take advantage of its improved breathing.
We're talking 30+ dump pipes to date, with only a very small number experiencing issues, and almost all of it was due to the install or something indirectly related like vacuum hoses and what not. 
which has nothing to do with the dump....
