Just bought a set of headers for my 03 F150 Heritage Edition. They come with new cats because they're long tube headers, but the cats are awful small looking and they have a flow through design, so I'm a wee bit nervous. Assuming the worst, (meaning my truck will be rendered emmisions illegal), is there a chip/tuner I can use to trick the emmisions testing equipment into thinking that my truck is running fine, or am I just being paranoid? To see the headers, check out the Google shopping results for "2003 Ford F-150 5.4L headers". They're from Sparktec Motorsports and are called OBX S.S. headers

 

I have the stock headers on my truck, but i replaced my cats with some small hi-flow ones. They are probably about 6" long. I havent emissions tested it, but no sensors have gone off. If you like a loud, mean sounding truck those should be great!!