Anyone run high-flow Cats to reduce hydrocarbon exhaust smell?

That's correct, but by turning the distributor one way or the other you can alter the fuel synch setting. That's another way of saying adjusting the timing of the injector pulse in relation to the cam position. Cams that are ground for higher than stock rpm can benefit from increasing the fuel synch reading up to double the factory fuel synch setting. It's a well documented performance tweek. However as stated earlier, moving the distributor on these set-up does nothing to affect the timing or fuel volume per injector pulse.

I agree. It is common to set it at about +4-5 degrees. I did this quite often to stock trucks. It has a nice effect on power especially on engines that have a larger cam. I used to check it and fine tune it if needed when I did a tune up or driveability work. They even recommended advancing it in factory training.