NO you can't!!!
Here is why. Follow me b/c this could get lengthy b/c I'm drunk.
I'll tell you right off the bat, you're going to run lean. Here is why...
A Mass Air Flow sensor works by heating the filaments (sp?) to a certain temperaure. The car tries to maintain that specific temp as air passes over the filarments on its way into the engine. THe air passing over said filaments attempts to cool them. The ECU increases the voltage to the filaments to maintain its preset temp as the air flow over it increases. The ECU has a table in it. For a certain inlet air temp (the other small sensor furth upstream from the maf determines this) it can tell exactly how much air is flow into the car by how much voltage it too to maintain that certain temp of the filaments.
NOW if you open up that area surrounding the MAF's filaments, you're going to let alot of air get by unmeasured....therefore you go lean...you go boom. Look at a C&L MAF Sensor. They sell various sized tubes while using the stock MAF Sensor Electronics to compensate for this. You're not the first to think of it. NO offense intended but it isn't as easy as you think it maybye b/c even a C&L MAF Sensor fucking sucks.
Basically by opening up the area around the filaments of the MAF Sensor, you're slowing the velocity of the air over those filaments there in not cooling them down enough so the computer is going to think there is less air coming in than there actually is and you'll run lean. I hope this makes sense.
IF you're talking about leaving the MAF housing ALONE and going to just 3" tubing (like a cold air intake) then thats fine but don't mess with the MAF's Housing itself. If you want to go bigger, pay the proffesionals.