I had some bypass pipes due to an issue with my previous cats grounding out over the smallest of bumps.

During that time I got the ve and maf dialed in and tested indipendantly on a dyno afr and all was sweet.

So I've now had some 200 cel's installed but in smaller cases than before and got them in, starting to do my VE and notice the car is now running quite a bit richer. My logic is saying this is because without the cats in place the engine was able to burn a richer mix of fuel/air. Does this make sense? In other words by putting a restriction in the exhaust system would the expected behaviour be to see the previous fueling being too rich?

Ta