[russdill]

You're never going to get the same atmosphere on Mars vs Earth. Not only are you going to need to make a lot of tradeoffs with respect to gas content (eg, that much nitrogen is going to be very difficult to find/relocate) but the same amount of atmospheric pressure is going to take a larger mass of atmosphere since there is less gravity.

So it really is a hard question to answer since to answer it you'd need to know what kind of atmosphere Mars would have.

[anticensor]

You could replace some of nitrogen by argon to defeat pressure issues.