exhaust wont give you much hp at all...no matter what kind you get. i have a magnaflow muffler on mine. sounds very deep and throaty, not ricey at all and it also gave me a good boost in mpg. dual exhaust will give more top end power, but low end will suffer, which isnt god if you wheel your truck.
Free flow muffler ( I have TRD and like it) with TRD air filer will only give you @ 5HP. Another @12 HP with headers (which are not worth the extra$$$ unless you are blown) It is only a sophisticated 6 cyl not a 389 CI V-8. Forget dual exhausts N/A for V-6. Flowmaster, Borla, TRD all good.
Yea, my 02 pre-runner is the BEST vehicle I have ever owned and I have had a dozen or more. Go to dealership. Know your prices and keep going back. They love to hook you the first time for 1K$ in their pocket but will settle for $200.00 just to make the sale and put something in their pocket.
A Flowmaster Delta 40 will give it a real good deep sound and if you cat happens to be bad replacing it with a high-flow (higher flow than stock) cat will also make it a bit louder. The cat I got was from cheapexaust.com and it is a lot less restrictive than the stock Toyota cat for less than half the price. The muffler, cat and the air box mod will give you some extra horsepower and great sound. As for headers if you leave the cat on, which you should, I don’t think the horsepower gain is worth the money you have to spend to get it. The cat is just way to restrictive and most of the shorty headers you get are more for show than power gain at least for the 3.4L V6.
I put a single in, dual out exhaust on my old 98 with a dynomax muffler. It sounded cool, but I lost 2mpg for some reason with no change in my driving style. 3 years later the muffler rusted out and I put my old exhaust back on, all of a sudden got 2mpg better mileage. Very odd.