All the 02-04 cars run rich. Ford installed #21lb injectors for those years but never updated the tune fro the 19s that were in there in previous years. Taking the cats off probably just let you smell it more.
However, I would scan for any codes as it could be an O2 problem. You will also trip the computer for the rear O2 sensors if you remove the rear cats without installing MIL eliminators.
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.