1999 Factory Headers?
 

Evening everyone. Just bought my first Mustang, a '99 GT. It's got tubular shorty header manifolds on it, which I was told were stock from the factory. Trouble is I can't find a catted mid pipe that fits between the headers and the Flowmaster cat-backs. Every New Edge GT I've looked at in the yards have had cast iron manifolds no matter what the year was. The person who told me it came from the factory with the tubular headers is a 20 plus year Ford Tech that I worked with when I worked in Parts Dept. This GT has got so many issues I'd think of just dumping it and putting my dollars into upgrades for my Supercoupe, but the Ford Gods (and my pride) won't let me.....soooooo onward and upward. Can anyone verify that this might have factory tubular headers? I'm not looking forward to replacing the entire exhaust from heads to tailpipe tips, but....

Your research is correct, factory built these with cast iron manifolds.

Kinda surprised you can't find a midpipe that will bolt up, any brand/manufacturer of short headers should work with the factory or any other midpipe. Only thing I can think is maybe your car has a set of JBA mid-length headers on it?

Pics from under the car of the headers and current midpipe might be helpful.

Factory Headers
 

The car came with a Bassani Off Road X pipe ( Someone was a horrible welder) and a flowmaster cat back. I bought a factory catted midpipe off a wrecked '02 GT. When I measured the distance between the two pipes where they mount to the headers, the Bassani's measured 22-1/2" and the one off the '02 measured 23". As for wether or not the headers are JBA's or someone else's I can't say at this time, though I thought I saw a Ford oval stamped on one of the headers when I looked at them a couple of weeks ago. Which seemed like a good sign at the time, as the gentleman had listed "Ford Stainless Racing Headers" on the list of non-stock items that were installed on the car. As soon as I can I'll go get it up on a lift and try and get some 'good' pictures. Might take a week or two because of my job.
Fred

They could be FORD Racing stainless Steel shorty headers which would have the oval.

Dude that's only a difference of 1/2". Loosen up a few clamps on the catback and adjust it as necessary.

this ^^

did you attempt to even install the mid pipe? the catback once unbolt from the mid pipe can move all over the place.. make that thing fit

I think you gentlemen are misunderstanding the problem. It's not that it's a length issue with the mid pipe to the cat-backs. It's the measurement between the ends of the headers where the mid pipe attaches. I put the car back up on the lift to check the headers for brands. They're Ford Motorsport Stainless Shorty Headers. If you put the end of a tape measure into the right mid-pipe opening and measure to the outside of the driver's side it measure's 22-1/2" for the Bassani mid-pipe but 23" for the factory mid-pipe with the converters.
I tried to add some pictures, but apparently my technology knowledge and skills leave something to be desired.

Never heard or seen Ford Motorsport Stainless Shorty Headers, FORD Racing or FORD Performance ya but not FORD Motorsports.

That being said the collectors or headers themselves could be bent IDK

https://cimg4.ibsrv.net/gimg/mustang...8e53fbe736.jpgWJL.... there's a tag welded/heliarced to the top of the passenger side header that says "Ford Motorsports" on it, so I'm assuming it isn't a set of aftermarket headers.
Sorry about the size of the picture, but couldn't get it to trim down a bunch.

^ Those actually are aftermarket headers. Been out of production for a long time now though.