I have a rear exit exhaust, full decat and Belanger cat back system. With the decat you do get a hell of a lot more fumes swirling around the car. I normally drive the car with both windows down and the aero from the rear diffuser and wing seem to swirl air round the car! All part of Viper ownership I guess
If you don't like your neighbors, the full decat is the way to go
As far as air intake goes, there are a couple of options
1st is to keep the original air box, add K&N filters and smooth tubes.
2nd as above but you can modify the air box removing the baffles inside to help with flow
3rd Add a Vipair airflow kit....now weather this is effective is of great debate and there are many threads on this so use the search feature to find more info
4th If you want a bling look, remove the air box and fit chrome tubes with K&N cone filters.
Problem with this once your engine gets up to temperature its hot under the hood and you end up sucking hot air into the engine, not ideal!
(this is my current set up, but I like the look)[/QUOTE]
Bend up a piece of aluminum sheet between the radiator and the support bar. Keeps the heat from the cones.