My IX studders a bit when boosting, at times.

When running testpipe w/ base flash it was running strong. Then I got P420 - catalytic element..., so I took it easy until the diagnose and code clearing.

Later that day, I put back on my Random cat since it looked to be clean. It's a used unit w/ maybe 10k miles or so. Then, I started noticing this studder.

Incidently, APR dropped from 11.5 to 11.3 or so w/ the cat.

Maybe its back to testpipe... any thoughts?

BTW, my resonated 3" testpipe was actually quieter than my non-resonated Random cat! Just that it stinks so much.

 

do you have a o2 simulator or spark plug anti-fouler?

 

yes, just added w/ the cat.