My opinion is yes and no. Using the small block chevy as an example, the engine performance peaked in the 1969/1970 era and quickly went downhill as emissions and gas mileage came to the front. The result was the engines were modified to have thinner wall castings (weight savings), lower compression, lower emissions (run hotter to lower emissions), more cast parts than forged, etc. HOWEVER, things like fuel injection started to make inroads....for emissions reasons at first. The result was better efficiency, more power, better engine control, etc. A performance engine today is miles ahead of the 1970 engine design. A good example is the Vortec head on a chevy..... much better than the old LT-1 head on a 70 Z/28. I think you have to take the different eras into consideration....if it's the 70's or 80's then yes, the engines are a step back.