The Highest Output Gas Ranges
Ah...The Viking range:

They updated most of their ranges to be 18,500 in the front burner and 15,000 BTUs on all the other burners. I like this range with self-cleaning, convection and updated controls. Then again, I should. This Viking is $4999 after a $750 rebate. See more about Viking ranges.
However, you do not have to buy a professional range for high output performance. Most gas ranges have at least one power burner equivalent to a professional range. These freestanding gas ranges also have warming drawers, while Viking and the other professional ranges do not.
Have a look at a number of regular freestanding ranges and their BTU output ratings:
KitchenAid KGRS308XSS $2049: 18,000 BTU, 14,000 BTU 2 9500BTU and a simmer burner at 5,000 BTU.

General Electric PGB980SETSS $2029: 2 19,000 BTU, 2 9500 BTU burners and a 5,000 BTU simmer.

Bosch HGS7282UC $1999: 15,000 BTU, 12,500 BTU, 9,500 and a simmer at 5,000 BTU.

Frigidaire FPGF3081KF $1089: Frigidaire is a good value at $1089 with a 17,000 BTU, 15,000 BTU, 2 9500 BTU and a sommer at 5,000.

Once again, if you need one or two high output burners, consider a freestanding range at less than half the cost of the comparable self cleaning professional range.
For more information about gas or professional ranges, try a Yale Buyers guide filled with terms, brands and features.