I not sure what you are asking here but if its a question on legal or illegal exhaust systems, there are several ways to go.
First, to keep it legal and or pass your state inspections then a convertor must be on your car. There are many companies that offer "high-flow" convertors that will promote better HP and you will pass emissions.
Second, If you are planning "off-Road " driving than straight throught exhaust is good option. This I am sure that you are already aware of at this time.
If you won't mind a post back to clarfy what it is you are trying to do, all of us would appreciate it.
A cheap, easy way to make your vette sound better is mufflers eliminators (straight pipes). Just have a muffler shop cut off your mufflers and weld a pipe and tips in their place. Won't gain you any power, but will sound great. A deep, mean rumble and not as loud as you would think. Costs about $100.
Be careful in what you ask for. If you get the wrong system the interior resonance will be M U R D E R!!! I punched out the baffel in the two inside pipes (basically makes it a straight thru exhaust) and yes it DID make a big difference in the sound. I liked it BUT the WIFE (keeper of the bucks and other things) HATED IT!!! Infact she hated to drive the car after that. (Thats one way to keep the car to your self ) Soooooo, in my attempt to keep peace in the family I purchased a set of Dyno Max mufflers and that fancy "Y" pipe that was suppose to eliminate resonance. It only helped a little bit and the resonance only changed a little further up in the RPM band. RIGHT IN THE 1500-2000 RPM band.
On long trips it gets on your nerves. Like they say " If its too loud I guess your too old" Im living with it!!!
Look at the flowmaster cat-back system. It's not stainless but it's a lot cheaper than the stainless systems. It is aluminized steel. I have had mine on the car for about six years now and they are still in good shape. They sound good and add a little power. I added headers and straight pipes and the power increase was really noticeable. This free flowing system will enhance any mods you make to the intake also. (larger throttle body, cam, head work, etc.)
As for Flowmasters, they do sound great, and add a good amount of power for an exhaust system, but for those who are concerned about looks (and most corvette owners are) the non-stainless tailpipes don't look as good out back as a nice shiny set of stainless tips do. Plus, I live in a very humid environment, and I get alot of surface rust on the flowmasters. The price was great (half the cost of most of the other systems) and I'm keeping the system on the car, except for the mufflers. I'm going to get a different set of mufflers with stainless tips (such as the muffler eliminators from Mid-America or the targa LT1 mufflers).
I studied the exhaust prob on my car for nearly a
year before deciding on a stock European muffler
for mine. Unlike the stock muffler, the Euro-muff
has 2 functional outlets per muffler. There was
only a slightly louder, lower, tone. There was
a top-end increase in mph also.. Very satified
with Walkers Stainless (Z51 type) muffler. It
matched the stock appearance too.. Good luck
with your choices.. Hopper