One civic owned by a granny that drives it gently, and gets her mechanic who is also her church elder to look it over regularly may last 250K miles or more.
Another civic that has been passed among several owners, who kept poor maintenance records and didn't replace fluids until red lights lit up on the dashboard, this may be lucky to make it 80k miles.
With regard to the "cold air intake" that will give you temporarily +5-10% power in fair weather, and may lose more than that permanently if you drive it in the rain. How about cold acid-rain direct induction into your motor?
And headers it sorta depends if your ECU needs an O2 sensor that is integrated in exhaust manifold, and does your new header substitute for this correctly? Or do you make a modification that results in a car that won't pass smog inspection, and has just become useless for anything but off-highway.