Yes you would. The o2 sensor in the y pipe does not just automatically disappear.....no y pipe....no bung....no sensor....get it? Unless you made a bung for that sensor in one of the pipes.....
99 SVTC, T-Red, #652/2760-12.8.1998
Mother#@%@!* did I sound abstract?
I hope it sounded more confusin than that!