That's about what my brand new 15,000 mile old DX motor gets. 250 per tank in the city. 420 is my record on the highway, non-stop for 8 hours on I-85 to I-95. I was sweating bullets trying to find a gas station at 2AM on a Sunday in BFE, too. 44mpg. That's with a CX gearbox, though.

It's about time for a valve adjustment. If you read your service manual, it states to do it every 15,000 miles. Maybe it's excessive to someone that has to pay for that service, but it's not so bad for a DIY'er. If you've had that intake for a year, it's probably well past time for you to buy a filter cleaning kit and take care of bidnexzz.