Driving a '97 HX for FE in New England can be largely an exercise in getting it into Lean Burn mode and keeping it there. At intake air temp (IAT) below 40 it doesn't stay in Lean Burn much. Wet or snowy conditions seem to also take it right out of LB mode. There's no instrumentation to help with that in the car but a ScanGauge will tell you what you need to know. It will read out throttle position, IAT, and will tell you when you're in and out of lean burn mode. And of course it gives you mpg data. The OEM air intake port is over near the passenger side fender. Even with substantial grill blocking the warmest I could get in highway driving was about 10 degrees F above ambient air temp. By cutting openings in the air filter box I'm able to get the [IAT] about 30 degrees above ambient air. It pulls air which has just come through the radiator. This temp increase means that I should be able to run in lean burn even with outside temps around 15-20 deg F or so. My original plan was to route a pipe to the exhaust manifold to pick up warm air there, but the car's configuration really works against this approach. The air box cuts seem to be doing a fine job. Today in 35-40 deg F temps with rain and snow, I was able to run in lean burn consistently, for the first time ever in such conditions. Note: doing this mod will produce a loud, deep moaning sound when you step on the gas more than about 1/3 travel. However, duct tape will cover your openings if you decide you don't like them for whatever reason. Here's a photo of the modified air box. I widened the gap at the notched attachment tab to make it easier to remove and reinstall.