the 02 simulator replaces your 02 sensor. All the 02 simulator does is provide a fake signal so your pcm detects that its there and working. Since the pcm knows its there and working, it will not throw up a DTC.

A shop will have to weld in the pipe if you want. You could buy this and then have them weld it in or just have them put in a pipe of their own.
ZZ Performance