I am in the process of restoring a 95 Cobra and after reading this post I discovered that the previous owner removed the rear crossover tube to the back of the heads and it doesn't appear they plugged the holes. The smog pump was still on the car but in modified form. I'm not sure why they did this but it's now gone. I've decided to remove the pump as I am not concerned about emissions. What are the effects of having not plugged these ports on the back of the heads? I'm chasing numerous gremlins and I need to eliminate factors. Any help would be appreciated.