The pipe is on and sounds really loud with the APEXi WS, I kinda like it though. Anyway, the O2 sensor will not fit. Can't screw it back in because it hits this huge metal part, looks like the axle, I think. The O2 sensor is currently zip tied to something but I'm not getting any codes. Also what is this O2 sensor blocker???

 

Nothing should be blocking it ....Try taking some pictures if you can...the reason its loud if because you don't have anything plugging the area of the o2 sensor.

 

 

They put a black plug in place of it. I know the pipe has 2 O2 holes(car is a '96). The one closer to the flex section is the one that's not fitting. Can't take pics but look at this one

http://maxima.cardomain.com/member_p...78_23_full.jpg', 575, 431
It's the big brown thing in the middle of the picture, that thing is blocking it. In my pipe the O2 sensor hole seems to be angle inward a bit and that's why it hits the thing...

 

Thats your Passenger side inner CV joint and I think your Y-pipe is defective or somehow you installed the o2 sensor wrong.

 

I haven't installed the O2 sensor at all. When the pipe is on the car the sensor won't fit at all. Can't put it in because the joint is bocking it...