Evolution1980,
Your question is one I've asked myself many times over the last few months. Right now I don't know what to do. What I did modify was pull the old restrictive exhaust system and replace it with the exhaust system from a 1982 with a free flowing converter.
Depending how things go I might run a Dyno comparison next spring between my current quasi-stock setup and then removing some of the polution equipment. At $80 a pull I don't know if I'm all that curious.
Living near Milwaukee we have strict emission testing, both visual and sniffer, for cars under 20 years old. Because I have a 22 year old car I can license it as a Hobbist or Collector car. The current rules for both classifications is pay a one time license fee of $140 (the plates are mine for life), have the car visually examined by a State Patrol Officer and then pass one last emission sniffer and visual test. After that the car becomes exempt from future emission testing for as long as I own it. Because the car has to go through one more emission test I have to run all the polution equipment at least for awhile.
All that being said I'm not sure what kind of performance increase I'd actually realize. The air pump system just provides additional air to increase combustion of unfired fuel in the exhaust and I can't see where that would hinder performance. There is some parasitic loss due to running the air pump off the crank but that shouldn't amount to more than a few HP.
The reason the 1982 has larger exhaust manifold dumps, 2 1/2" versus the 1981 2", and a dramatically increased front and rear exhaust pipe diameter was to increase the flow and provide hotter exhaust to the converter to meet tighter emission standards. Where the 1982 Front and rear Y-pipes converge into a single pipe it's oval shaped which I'd guess to be 3" to 3 1/2" in diamter if they were round. With the current setup the engine should be breathing pretty good.
Sorry for being long wided but I've spent a whole lot of time thinking about what to do not to mention spending over $550 on the current exhaust system. If anyone has any experience with emission versus no emission HP comparisons I'd love to get feedback.
BTW - I keep looking at your tribute paint scheme and have considered doing something similar. Remember imitation is the sincerest form of flattery.
Eugene