I have an 03 Infiniti G35 sedan and he been able to leave it alone since I acquired as the g35 bug a few years ago. I started recently running out of things to do as far as upgrades to the motor and bought test pipes and installed them. I must say that I am not impressed with the results. It sounds like hell and I have a bunch that it's because of the 02 sensor issue that I knew was going to be an issue when putting on test pipes. So my question being is that my real issue? And if I bought new 02 sensors wouldn't I just ruin those if I'm not running cats? What should I do?

 

Generally straight test pipes don't sound all that well. The only test pipes I've heard that actually make the car sound better is motordyne ART pipes. As for the o2 sensors, you should get some defoulers that pull the o2 sensors out of the direct exhaust gas stream. Something like these:
https://www.shopbtr.com/J-Style-O2-S...er_p_4476.html

Just check on the threads, I found those after a quick search, but not sure if its the right thread sizes for nissan o2 sensors

 

Test pipes will make your car sound raspy, that's literally what they do.

You can correct some of this by adding another resonator, the midpipe is usually where people put one.

 

I watched a YouTube vid where these headers were paired with the Arc catback on a G35. Sounds pretty epic.

 

I just installed some test pipes from invidia which I brought from import alliance car show, they sound much better than the cats... A VQ wants to make noice don’t deprive it of doing so. I would just say also make sure to grab a nice intake so it can breath a lil better... IMO if you want a lil extra sound and not to raspy and sounding OD