My '68 Barracuda Convertible has a moderate cam (.246 & .252 @ .050 on 108*) in my remapped factory ECM for my EFI system. At idle, the exhaust fumes used to waft into the car and bystanders would scrunch their faces and swat away at the air when I idled by. Tuning had no real effect on reducing the burning eye fumes likely from the significant overlap of the cam.

I welded on a pair of 4 inch racing cats with the plated metal honeycomb instead of the ceramic honeycomb, just behind the collectors. The smell vanished. There was no detectable power loss and it didn't change the sound of the exhaust.