can't seem to find a manufacturer, I've checked out BBK, JBA, and MAC. they have unequal lengths only, or so it seems.

i guess headers get moved off my list unless i make a friend at a smog stop.  from everything i could find, it seems that unequal lengths are kinda worthless unless you have a turbo or supercharger setup.

i found the following on the internet from allfordmustangs.com.  they used a stock 5.0 for each of the tests.  Hopefully it will help someone down the line.

oh, has anybody come across something like this for a 4.6?  apparently the 4.6 reacts better with 1.5" tubes as oppsed to 1 5/8".  at least for stock and lightly modified applications

here's the torque graphs

bummer, looks like there's just no getting around a supercharger.  hehehe.......