Hi
I have

- replaced the EGR valve
- resealed the exhaust manifold/downpipe junction (not sure it was necessary)
- shortened the R16 resistor
- disabled ignition vaccum timing advance
- drove the car hard just before the test

and I passed!

Here are the numbers (all in grams per mile)
HC (limit 1.2), 1st test: 0.98, retest: 0.21
CO (limit 20) 1st test: 6.13, retest: 3.62
NOx (limit 2.5), 1st test: 3.01, retest: 1.45
CO2, 1st test: 445.99, retest: 457.01
O2, 1st test: about 0.4%, retest: nd
All values have significantly improved.
Thanks to everyone, especially to Duke!
Have a nice weekend, Bruno