I have a 1998 A4 with a PES Supercharger kit on it which was already installed when I bought it 5 years ago. It just failed the emissions for the first time ever with a high NOx of 2.66 where the limit is 1.50.

The only change that I'm aware of is hotter plugs installed by our mechanic this summer when they were correcting a hard starting issue and which I was told were the right plugs for a vehicle with this supercharger.

Been reading a lot about Seafoam being used through the brake booster or other vac line to assist in curing high NOx.

I've been reading some conflicting information about this procedure and if it is safe for Superchargers in general but found nothing about the Eaton charger. Does anyone know for sure?

Thanks
Bernie