singh grooves

was at a friends yesterday not been for a long time but he wanted some fins repairing ,he as been in the racing game for years and builds er6 engines and gets very high figures but thats another forum.well i am a nosey get and was looking at some head work he was doing and noticed grooves cut in the inlet tracks ,he will not tell me his secrets but did tell me what they were singh grooves. wheel had some good reading last night and as i have a full gas flowed head well you read for yourself the results