You may be right. My thought was after reading posts from guys porting these 920 heads is that they are in the 135 cc port volume area. The j heads factory are in the 170 area. That last number may be wrong but assuming it is 170 that's 25% more volume moving the same cfm. Thats without calculating in the increase piston speed as little as it may be and I get heads capable of similar hp as factory J heads with a much more efficient 1000 to 3500 rpm and a much better quench allowing me to take advantage of as much timing as possible. No?
