Although the video is in Chinese,
It clearly demonstrates the various RF boosting antenna mods available for the Mini.
The Parabolic mirror does give a small but noticable boost...  (I've used the mirrors myself on a CE mini & got to 2290m (1.42 miles)),
But the plate based antenna that require controller modding, actually do give a significant signal boost!
The Yagi, is the worst... But this seems to be the 5.8ghz only one that is tested...
Video

Here's a 2.4Ghz Yagi that might actually work ... offering 8db gain.   Taking the CE transmitter from 19db to 27db  Maple-Wireless-Yagi

Their 5.8ghz Booster adds 14db to the CE transmitter, upping the 5.8 gain from 14db to 28db!    Maple-Wireless-5.8ghz-antenna

I wish this was an independent test and not from a company selling a product, I can't believe anything they say knowing they have there own product to sell me that's "better" then what they are showing examples of. I have parabolic and feel they didn't do much, when I get my yagi's I'll know if they actually do anything or are just more snake oil. As for the hardware mod, that's been the case from the beginning. Nothings going to improve the signal better then replacing the antenna, anything you attach to it can only modify what's already being outputted.