While 175s work fine on the Mirage, I am not sure why anyone would want to switch to them. Five years ago, there were only two options for replacement 165/65 tires...the OEM Dunlops, and Bridgestone Potenzas. Both were quite expensive, and had to be special ordered. This is why people with Mirages started running 175s in the first place.
Nowadays, tires in the correct size are much cheaper, much easier to find, and available from a number of manufacturers. If good 165s are available for $40ish dollars, why switch to $40 175s?