Which ever way you decide, remember that these engines have a full 180 degree firing order. With all things being equal this firing order allows for evenly spaced exhaust gas pulses, which is ideal for an efficient exhaust system.
If you decide on the header with the duel collector follow Gene's example. I would suggest thou that you have the muffler shop wait to install the "H" crossover. After the exhaust is installed clean and paint the exhaust pipe from the collectors to the mufflers with white paint. Take a run with your new system and watch out for that "Drone" and make a note of the RPM. Find a route that will make it possible to run at this RPM for a long period of time and then take it back to the shop and inspect. Look for a brown dis-colorization on each of the pipes. If there is a natural frequency / turbulence occurring it will show up as heat and turn the paint a brownish color. It is at this point on the pipe that you want to install the crossover to cancel this frequency or resonance. If the system does not have a natural resonance or exhaust drone that you can hear there is no need for the crossover.
Take a look at Mustang Geezers site and the system he put together:
http://www.geocities.com/mustang_man_19 ... ystem.html
I would suggest that you stay away from the "X" pipe. This configuration actually has the exhaust gases from each collector interfering with each other. This can't be good when working with a system that already has evenly spaced exhaust pulses.
This subject has already been discussed a number if times here on the forum. Do a search on the forum and on the web (exhaust drone). Check out all of the different exhaust system that have been installed and are in use on these six’s.
My 66' is being delivered to Performance Exhaust in Algona, Wa. this coming Monday. I have asked that the shop install 2.5" exhaust pipe from the 2.5" 6 to 1 collector to a transversely installed muffler (muffler style 21) with dual out 2" tail pipes through the new GT valance. At the installers suggestion, there will not be any other adjustments to the system until the natural resonance of the system can be found, if any. I am lucky that the installer already practices this method of exhaust tone tuning.
Good luck with your system, Ric.
One of the nicest exhaust systems that I EVER saw was on a friends Corvette(yeah,yeah,I know NOT a Sweet Ford 6).However,the thing kept eating exhaust systems.Never got more than 6 to 8 months out of one.
Just remember to enjoy the journey. One set of Pacemakers here outlasted three cars, finally dying on the fourth (rust through, uncoated).
