Air Breather Tanks
As the induction system operates at full efficiency on oxygenated air then fitting a catch tank will gain horsepower, as well as prevent carbon & sludge build up in the induction system.
Simply removing the emissions & breather system will tend to result in a very grimy engine bay, as well as being detrimental to the environment, and an MOT fail - for race use cars showing any indications of oil fumes from their breather system will be required to fit a catch tank by the scrutineers. This tank is fitted with twin inputs so it will suit inline engine configurations, V configurations, and twin cams.
If only one inlet is to be used then either block off the spare one or empty the can before it reaches its capacity (every 1000 to 3000 miles).