Well, on my ' 84 I took off everything but the EGR valve. I have a GM HEI and a Weber 32/36, and I'm quite sure it performs far better than with all that emissions crap on it. The reduced weight alone from all the miles of wires and hoses and all those little vacuum switches probably increased my gas mileage. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.