Reply to "High compression and pump gas"

Yes, piston design is very important in the combination and most often overlooked as it is too easy to buy "off the shelf" pistons. In a perfect world the piston would be matched to a specific head. Quench pad matching is very important especially on dished pistons. On flat tops its not as much of an issue as the entire piston is on the same level as the quench pads. For domed pistons matching the piston to the head can help flame propagation through the combustion chamber. Big domes affect burn speed because the flame front has to travel around these raised areas.

Fuel injection is certainly leaps and bounds better than carburetion for atomization. With the modern injection systems we can dictate not only how much fuel we are injecting but also at what point in the engines cycle. At low rpm's and idle we can start the injection when the intake valve is open and the port velocity is highest. The makes a very noticeable increase in idle quality as well as gereral driveabilty. At high rpm's when we are running higher duty cycles and cannot fit the injection event into ideal times it is less important because port velocity is so high.
Direct injection goes even farther above this. At this point we are injecting super high pressure, cold, highly atomized fuel directly into the combustion chamber exactly when we need it. This allows previously unheard of compression ratios that are able to run on pump gas. You would be amazed at the boost these engines can run in stock form. The drawback being increased maintenance due to fouled intake valves. In a nutshell technology has advanced to the point where 11 to 1 is on todays motors is no longer "High Compression".