[WegsZX3]

I have a 2004 ZX3 with a 2.3l and manual transmission. The 2.3 seems to have enough power to get me up the on ramps with no issues and cruise the grades at 65 mph. Accelerating up a grade is tedious. I put about 30K on it each year with mostly freeway commute. I use 5-30 synthetic oil changed every 5K miles, change the plugs and fuel filter every year and drive 65 mpg ave during the commute. I also use fuel injector cleaner at every oil change. I keep the stock size tires at 34 psi (as recommended). The biggest variations in mpg for me are highway speed and tire pressure. MPG drops to 30 if I run the tires at 32 or lower. MPG drops to 28 if I average 70 and 26 if I average 75 mph. I've seen no difference in fuel type (although ARCO 87 was the worst economy) or octane rating. If I take easy back roads and average 50 mph I've gotten a high of 36 mph. City only is typically 24-26. I'm looking to evaluate intake, and exhaust options next to try to get average up to 35. Would love to have better performance and better fuel economy with the same investment. I love the Focus and will definitely buy another when this one hits 180K or so.