failed emissions

[Brandon Rogers]

Guys-
well my car failed emissions - first time I've ever had an issue with any
car.  Just got off the phone with a "supervisor - let me tell you we are all
in good hands - I'm highly confident that the people in charge of these
programs are hard at work and are very competent.
 
Anyway....car failed due to NOx.  Got 5.2 with 4.5 allowable.  This is an
ur-quattro that has been on the road with the 3B for 6 yrs - has passed 3
times prior. 
 
What are others experiences with emissions failures due to NOx? (BTW the NOx
limit (in CO at least) was just reduced from 8.0 to 4.5.)  My previous test
I got 3.5 with 8.0 allowable.
 
So far I:
put my cat back on (had passed before with the test pipe)
new O2 sensor
Went back to stock F5DPOR plug from F6DTC
will un-tighten the wastegate spring (just in case)
will be pressure testing for vacuum/boost leaks tonight
 
TIA-
 
Brandon 
Denver, CO