Phillipe,
In addition to all the excellent suggestions and advice above, one thing you MUST do if you lower the car is to roll the fender lips up against the fender so that the lowered tires (especially the fronts) don't catch the lip and tear the fender when turning the wheels. (details at the bottom of this link: http://www.markscars.ca/Pantera_Projects.html)
You will need to do the rears also if you plan to install 10" wide rear wheels and wider (295/50/15) tires. It's all worth it though, as noted by others. Much better handling and appearance. Good luck!
Mark
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