the break down is a bit subjective.

imagine a garden hose and a set amount of water volume. you will get a pretty high amount of pressure. now take that same amount of water (volume) and run it through a PVC pipe. the volume is the same but the pressure is WAY lower. so now what? how that the pipe is bigger what do you have to do to get the pressure back up? you increase the volume dramatically.

long story short, yes the T28 (in SOME cases) may produce more pressure but it's not really pressure alone that makes a turbo system great, it's the amount of volume it can move at that pressure.

besides the specs are a bit skewed too. the ones listed are possibly the biggest T28 and smallest T3 in common use.