The CAI didn't do a whole lot on my truck as far as performance, but it does sound better, I haven't had to pay to replace an air filter in 30,000 miles, and it improved the fuel mileage a bit as well. As for the exhaust, duals are just for looks. A high flow single outlet will get you the exact same gains, and maybe even better gains than duals. I've got a single out stainless steel Gibson on my truck, and I'd buy it again in no time. It sounds good (in my opinion) and gave me a noticeable boost in performance and fuel economy.