And how can we resolve issues with getting high nox in the exhaust ? thanks!

 

I have the same problem with my 00 Civic EX (D16Y8)... no egr system, it uses the PCV system. The only way to really control it is balancing the A/F ratio keeping it Stoich, and cooling the combustion temperatures down with a lower thermostat and cooler spark plugs.

 

Retard the timing to lower NOX, HC will slightly higher with less power and if you can't lower it by doing that, look on buying a three way cat.