you may or may not know this but.........
since 1990 it has been against federal law to tamper with, remove, or alter any emissions equipment on any vehicle - this means you may NOT install a test pipe, hi flow cat, or whatever - you must run the OEM cat or an approved replacement - you cannot even replace the cat in the first 50000 miles without legitimate documented need - this is in ALL states
most states already have emissions testing, and the standards get tighter every year, in compliance with EPA law, which tests the air quality area by area, and establishes "pollution zones" that require more stringent inspections - as more people crowd into an area, the air quality goes down and the standards go up - so, while you may currently escape testing, next year you may not - they aren't granting free passes either - since the cash for clunkers program, the states are motivated to get the cars off the road, and are not as inclined to allow things to pass - you may soon find that you need to get special registration for an older car - implementation of a new law is currently under review that would require special registration of older cars (pre OBD2) and cars that do not meet the standards - under this law these cars would have limited access to use of highways, much as cars with collector plates in most states have now
while currently each state has its own specific sets of laws regarding inspection and emissions standards, this does not supersede the federal laws
so, regardless of whether or not your state inspects your car for emissions, you still have to run the OEM cat - some states have implemented "on the road" inspection stations in an effort to raise revenues (not just california either) - if they happen to pull you over, they can impound the car, and force you to restore the equipment at their facility, at your expense - the fines are pretty hefty too - each state that participates in this program gets additional federal funding, so they are motivated to do this - given the economy, i would not expect this movement to subside very quickly either
shops that install such illegal components, and/or alter these systems are subject to heavy fines, loss of the business license, and the EPA can even shut the business down
proceed at your own risk