The new spark plugs (and spark plug wires purchased separately) work great, and the factory gap of 0.44 inches held up during shipping (however, you always, always, always want to gap check your spark plugs! Do not neglect this!).My 12 year-old Honda Accord (150k miles) runs almost like it did when I first bought it, and I've increased my per tank mileage by about 10-20 miles. It's not a huge difference, but that adds up over time.I'll update this in a year or earlier if anything goes wrong, but they've been installed for a month, and so far, all is well.One year update: Still running strong; I've had no mechanical problems since changing them, spark plugs or otherwise.