As an experiment, I set up my grill meat thermometer with the probe right in front of the air intake on my stock 76 2.0, with the digital display stashed above the passenger seat (probe cord was only long enough to reach there). Wish I had one of the wireless ones, but maybe next time. I then drove the car about 20 miles on the interstate. The device can be set to a desired temperature, and will beep when that temperature is reached. I set it to 130 degrees, and it started beeping about a mile before I got off, and continued to beep for a minute or so after that. The ambient air temperature was about 40 degrees, so that's at least a 90 degree increase, or about a 10% horsepower loss if you use the SAE formula for dyno correction of 1.1% for every 10 degree increase in temperature.
This is a follow-on from my post asking about experiences with a guy selling a cold air intake kit, but I'd be curious if my experience can be duplicated by others. It would seem like getting cold(er) air to the intake would be a good improvement to make.