I bought a used UPR X-pipe (no cats)... i noticed that there are 4 holes (for the O2 sensors im guessing)
When i get the X installed should i also have the simulators installed to cover the holes?... or how will it affect the exhaust to leave them open like that at least for a short period of time?
When i get the X installed should i also have the simulators installed to cover the holes?... or how will it affect the exhaust to leave them open like that at least for a short period of time?