I can appreciate and certainly take the constructive criticism. I know personally in the past I used a 225 12" spring and leather wrapped both ends of the spring to keep it all quiet. That all worked very well for me on the street. I can also see the benefit to a light spring as well. I am currently using a 12 130 lb spring in my ttop car with travel limiters but that is getting into a whole different ball of wax.I am glad you have not had any issues with your UPR rear suspension, however the discussion was about front coilovers. I respectfully disagree with your spring rate recommendation. I think that high a spring rate would lead to premature wear on the stock shocks and a way to stiff ride. There is ample evidence of posts made throughout the years on several Mustang boards as well as my personal observations of front end clunking and other noises on cars using their front coilovers. Sometimes the noise is remedied by wrapping the struts in duct tape, other times it was not solved.
Not trying to bash anyone, just reporting what I think is factual and helpful for others.