On an Impreza it's pretty hard to tell if the exhaust is blowing or if it's running on 3 cylinders etc I am shocked that we didn't notice it though.

She is well into her cars and it's quite nicely modified I have it at the moment to fit equal length headers, new downpipe, exhaust system, bigger injectors, bigger MAF and a remap because it's running an Apexi power FC She hasn't heard it running since the new exhaust but she is popping over in the morning to collect something so she will hear it then.