we have a 3/2 header into 2 inch pipe going down from that into 1-5/8 inch pipe at the first bend towards the muffler to the stock replacement 1-5/8 small twin pipe 14x6 muffler. we do not have that resonator in the middle of the exhaust system. the exhaust is very restrictive right now, but sounds pretty good considering. i bet we are losing at least 15-20 HP with that tiny exhaust on there. we are headed to the muffler shop soon to go with 2-1/2 inch from the header all the way back into a bigger turbo muffler.
car was purchased a couple months ago for my son in the San Francisco east bay area.
that is Mt. Diablo (Walnut Creek city side) in the background in the video
had quite a few quirks to be fixed and "engine adjustments" to be made.
the carbs were way out of sync and idle mixture was horrible and engine was performing terrible, but reading up on SU carbs was new to me, but was very easy to learn and then adjusted them in less than 45 minutes.
just somewhat easy to fix but pain in the butt to track down problems made a huge difference in performance with this car.
Nice car! Hope you and the son plan on keeping it orange, my personel favorite. I spotted Mt. Diablo in your video, I see if from a distance on my way to work (Vacaville). Good to see you got it performing the way it should be...proper tuning can make such a big difference. Checkout my '72 at http://home.comcast.net/~thcastro