Intake and exhaust mods for the purpose of increased power is a waste of money. The best of them lose 4 or 5 HP below 3000rpm and gain it above 3,000. That means you just shifted a little power away from the area where you drive, to an area where you don't. These vehicles come from the factory with CAI. The difference between the incoming air temp measured by the trucks sensor and the outside air is just 2 to 3 degrees higher. Intake and exhaust do nothing unless you are running forced air induction or have done extensive head work, including cams. If the head can't breathe, then opening up either end is pointless, if not detrimental.
Most of the aftermarket CAI intakes leave your truck more vulnerable to inhaling water, and I don't think any of them provide as good a filtration as the stock induction. They increase intake noise which makes a nice placebo effect in lieu of real power gains.
Headers and other exhaust mods do have the advantage of eliminating the cats. A lot of people like the way they look and sound. Eventually I'm doing this mod to reduce the risk of fire from the cats running through deep grass. I'm also not about to pay for replacements if they get clogged. I'll probably run a stock muffler though to try and maintain a little backpressure.
The only legitimate bolt on power is a supercharger.
Regear if you want quicker starts. I put off regearing my FJC after going to a larger tire size until the rear diff broke. Once I regeared I realized what everyone was talking about. Huge difference and didn't really hurt my mileage too bad - I dropped 1 MPG on an average.
Skipper of Dig-Dug
hiker of the Benton Mackaye Trail
Toy-FJC on 35's
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