Hardy,
Can't speak for TX, but in Colorado, what you've heard is correct.
If you wanted to run a full true dual exhaust system, you would have to have two cats, two mufflers, and two tail-pipes.
One way around it, that you might consider is a "CAT-Back" exhaust system. In that case, they use the stock single pipe through the cat, and split the exhaust from there back.
While you won't see as much of a difference as you would on the full duals, it does make a pretty significant difference, when compared to stock. I did this on my 94 F-250 (460 CID) and it made a big difference. Sound real nice too.
I had Exhaust Pro's do the work, and if I remember correctly, with the mufflers, pipes, and stainless tips, I paid around $280.
Hope that helps.
