I have often thought about doing this kit, and in so deciding, have done alot of research on the kit.
I will put in a quote from Len Roberto, Who reviewed the kit for Modeling Madness.com:
"This big Mustang kit has received its share of criticism- most of it justified. There are problems not easily fixed by even the best scratch builders: canopy is misshaped, cowling has shape problems, cockpit is sparse, rear fuselage dimensions look a bit off. There are probably more but like I said I am no expert. And I agree with the folks who say that this subject is the most accessible WWII fighter in the world and Trumpeter should have no excuses in producing an exacting replica with all the info and examples at its fingertips. At the price they are asking- these things should have been dealt with better."
Hope this helps clear up a bit...
demono69