I want a new range hood, how many CFM (Cubic feet per minute), would i need for mostly Asian/stir fry cooking?
Use these as personal experiences and not as guidelines for construction or for code-compliant renovations.

You can use the commercial kitchen code as a guideline: for every square foot of hood codes suggest between 50 to 100 CFM (cubic foot per minute) of exhaust capacity.  With those guidelines, a hood covering a 36 by 20 inch cooking surface (720 sq. in. or 5 sq. feet) should require 5 time 75 (the average) or 375 CFM.  

Now the problem.  While many hoods will provide more capacity than that my experience is that they are not enough.  Unlike commercial kitchens, home kitchen are missing the blowers that pumps air in.  The code for commercial kitchens suggests an in blower at about 90% of the exhaust capacity.  If weather permits you can open doors or windows, but that is never like having the air coming in right next to the stove.

This question has also been asked in the DIY Stackexchange as "How many CFM for a range hood do I REALLY need?"