i have some thoughts on your question. i have read that book (and severl others) quite a few times, and here is my understanding of things. bear in mind that i could be completely wrong
WARNING, long post...
essentially yes. we are talking about flow vs. pressure ratio (10psi). thinking that different turbos produce different cfms at the same boost is a misconception IMO (unless i am way off on my thinking - if so please correct me!). to see that the flow is the same, just look at the two compressor maps. here's an exercise: using Frank's turbo calc, put in some data points for your car (values don't really matter). adjust the HP until the calc tells you you need 10psi. then select some different turbos, like the 40, 46, 57 and 60 (under the T04E Series). take a look at the first 1.68 (10psi) point in each map, then look down at the airflow. this is the amount of cfm (in lbs/min) that the turbo will flow. notice for each turbo, that point is at the same cfm. thus different turbos will (roughly) produce the same cfm at a given pressure ratio.
okay, so if 10psi = 10psi, why do some turbos pull better or produce more power? the reason is because of the adiabatic efficiency of the the turbo at a specific pressure ratio (PR) and the RPMs of the shaft. if you look back at those maps, you'll notice that the efficiency "islands" shift around the points. if a point on one turbo is lower in efficiency then the same point on another turbo, the first turbo will heat up the charge more then the second. and heat = less dense charge = less fuel that can be injected = less power. essentially, a smaller turbo operating in it's peak efficiency range will produce MORE power then a larger turbo operating way outside it's peak efficiency range at a given PR. this is because the larger turbo is heating the charge more as it compresses the air.
also, you have to take the shaft speed into account. in order for a turbo to produce the desired PR (1.68, 10psi), the compressor and turbine must be spinning at a certain RPM. exhaust is what gets this shaft spinning. larger turbos [in general] don't need to spin as fast to produce the desired PR. so why doesn't my larger turbo produce boost faster then, since it can spin SLOWER and make the same PR!? the reason is because the weight of the compressor wheel is a lot heavier then that of a smaller wheel, which means it takes more exhaust energy to get it spinning. so even though the larger turbo can spin slower, it takes LONGER to get to that slower speed then it does for a smaller turbo. this why BB turbos are great - they can have the benefit of the larger compressor wheel (and slower shaft speed), but since the resistance to get the compressor wheel spinning is lower (thanks to the ball bearings), it can spool faster and create boost sooner.
so, given the above, the reason you feel a difference is that the mitsu is small, so therefore it doesn't take long to produce boost. so, based off the seat-of-the-pants feel, it feels like it pulls hard. cause your butt tells you so. the larger turbo, though, takes a lot longer to produce the same boost (because of the compressor wheel weight). so boost onset is more gradual, and your butt-o-meter says i'm not accelerating as much. question: are your above statements based off seat-of-the-pants feel, or your took the car to a dyno or drag stip? also, you will get max boost on the mitsu SOONER in the rpm range then the larger turbo. this is where your engine/cam come into play. if you make most of your power/torque lower in the rpm range, the mitsu which gives you max boost sooner, will have a larger affect on overall performance (because it's boosting more power under the curve), whereas the larger turbo reaches max boost later on in the range, quite possibly where your engine is running out of breath - thus no power for the turbo to boost. this is why OEMs typically use smaller turbos on stock street-driven cars, because the cars spend most of their life at lower RPMs and it gives a more "peppy, i have crap loads of power" feel (and then falls on it's face at higher RPMs).
in summary: 10psi=10psi at roughly the same flow, but that does NOT equal the same power (due to charge air temp, density ratio, etc). a larger turbo will require more exhaust engery to get going, and thusly will require more time (or more flow) to get going.
all of this is why proper turbo-sizing is important.
thoughts everyone? i hope this helps...assuming i'm not completely wrong. do you guys think i am way off here?