Duel exhaust

Depends on many variables. If you are willing to spend the money for the correct cats and use the correct size pipe and good mufflers, yes you can gain some upper rpm range horsepower and torque, but you will likely lose some power at the bottom end. And the amount of horsepower gained will not be that much doing just the exhaust, but if your doing alot of highway towing, it will help. If the engine cant breathe in, improving breathing out wont do a lot. Eldebrock has a nice manifold for TPI fuel injection engines, and a decent one for throttle body. The TPI can be bought as a complete set up, base and runners, or just the high flow runners can be purchased and Eldebrock says they will work with the stock base. Holley/Weiand don't offer any that work with stock injection systems that I know of. Nether has Offenhauser and that's sad.

Whitelightning

Not really, but it'll look cooler and sound better! If you want more HP get a set of full length headers and mate them to high-flow cats with the dual exhaust/perf. mufflers; that'll net you 20-30 horsies.

Doc

For anything other than high HP and/or all out driving, I wouldn't recommend dual exhaust on anything. A single 3inch exhaust flows as good or better than dual 2 1/2inch exhaust. I have gotten nothing but compliments on the sound of my single 3inch from MANY with professional duals, so the excuse about duals sounding better is dead.

There ARE exceptions to everything...

Ed,

If you just want a good sound, I'd suggest a Flowmaster 3" single side exit. If you want HP, then do as Doc suggested and go with full length headers. Thorley Tri Y's are they way to go. A little expensive, but worth it.

KB