Shouldn't I be getting BETTER gas mileage with the catalytic converter removed?

Hello from New Zealand! I just bought a 2004 Ford Escape 3.0 V6 with ~70K miles on it. The catalytic converter had been professionally removed before I purchased it, and over the last 2 tanks I've been getting terrible gas mileage (around 14 mpg with 50/50 mixed driving). From what I've heard, removing the cat can (with appropriate tweeks) give you BETTER gas mileage and not worse. Also consider that in New Zealand they don't water down their gas with ethanol. So what gives?

I've had it hooked up at the mechanics and it's not running rich or kicking back any codes, at least according to the upper 02 sensor (which was left in place).

Now let me lastly say before I get the onslaught of colloquial fuel economy "wisdom", that I'm a hazmat commercial driver with over 100K miles on the road, so NO it's not driving habits, and YES I have run through the normal gambit of oil change, filter check, tire rotation/alignment, suspension etc etc.

I owned this exact vehicle in the U.S., and even with the cat on I would average 19MPGs driving like a maniac on terrible tires, bad oil and shot suspension. So I'm not going to be easily convinced that this is anything but a fuel system issue.

That being said, gas is $1.79 a liter here and I need better economy, ahh!

Thanks everybody!

P.S. It's not illegal to remove the cat in New Zealand.