I am thinking about installing coil over springs on my 1970 Mach 1. I currently have a stock setup which includes Mustang's Plus 620# coil springs and Koni shocks with the Shelby drop. I rebuilt the upper and lower control arms with new bushings and also reinforced the control arms by welding a steel plate on the bottom of each. It looks like the Global West lower setup. I did not have much cash back then and had to do it the cheap mans way!! Now that I have a little extra cash in my pocket, I would like to know how much of a performance improvement the coil overs would make compared to my current setup listed above. The car will be for the street and will not see the a road course. If anyone has any hands on expierence with both of these setups and can compare them, it would be appreciated. What are the pro's and con's of each? Thanks.