Originally Posted by imprezajohn
Ok, This is my first Subaru, I've spent many, many years in the American Muscle Car world and my understanding of these vehicles is pretty much zero. With that being said, what are, if any, the first N/A performance mods folks do to these vehicles? I drive 160 miles a day round trip to work, so reliability and gas mileage are an issue. Any help will be appreciated. Thanks.
Mileage comes in two parts:
Stop and go traffic relies heavily on car weight for energy losses. Long distance driving is all about friction and the big factor of aerodynamics. Most modern engines are very good about completely burning the fuel that is run through the car. Mods can help put more air and fuel into the car and make more power, but efficiency doesn't really change. You just get to make more power. Some gains that you can do for efficiency is to pull in as cold of air as possible and to burn it as hot as you can without damaging parts, and you can up compression and change cams for more efficient operation.
For long distance, I would point you more towards improving aerodynamics and reducing friction. Every little bit helps. Run efficient tires and run them at high pressure. Run good synthetic oil and gear lube to keep machine friction low. Carefully select or remove trip pieces that improve aerodynamics (removing roof rack, installing smaller mirrors (some cars came with a couple options), adding a skid plate and some under tray bits to reduce under chassis drag, etc.).
For in town, find places you can remove some weight from the car. Run a lightweight batter, JDM, or race built bumper beams (very light), swap to aluminum suspension componments, pull the spare (maybe swap t runflats), swap on a CF hood and trunk. You can just run through the whole slew of parts and just try and drop weight. Even something like a lightweight flywheel drops 10 lbs. and reduces a a sizable amount of rotational energy used to accelerate the motor and car.