HI, I have just brought the wrx standard scooby and would like a bit more power. Speaking to some people and they say one of the easy ways is to change the down pipe. I have a ninja backbox on at the mo and looking to replace the down pipe with a ' SUBARU IMPREZA WRX STi RA CAT DOWNPIPE EXHAUST DECAT' from ebay item number 270298891545. Is this a good choice and will it affect my engine managment lights cos of the lambda sensors? please help.