I'm looking for suggestions (creative and otherwise) on how to improve gas mileage on a '97 GMC K2500 with a 454 big block engine (gears are 4.10, I think??). I know about all the basics - keep tire pressure up, new plugs/wires, etc., keep your foot off the gas as much as possible, etc., etc. I'm also aware that these engines weren't made for mileage. They're made for working and towing. All that aside, what about adding headers? Will this help the mileage or hurt it? What about a performance exhaust? Would a K&N air filter help? Has anyhone had success doing any of these things? What have you had success with? Thanks very much for your input. I look forward to reading your replies.