Just checked our 2002 Silhouette with the Groove. Plugged off the pcv yesterday and checked the exhaust today - it definitely smells better. I was hesitant, not knowing how it smelled before the mod, but it DOES smell like a dryer vent. I will try to contact our local Exhaust Gas Analyser manuf. for a test and see how it measures up - who knows, I might get more than a few surprised looks and a few Mods in return!
Scott