Yeah, basically all that you have to do is "fold" the inner fender lip up. It gives you more clearance for your tires and is realitively easy to do. Here is a site that shows the most famous, baseball bat method. (I know its an Acura Integra, but it shows how to do it.) Also, some people use a heat gun to heat it up so it rolls easier, Just make sure you take your time! You don't wanna go messin it up.
http://integra.vtec.net/wheels/rollfender.html
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1988 Mustang 5.0 LX Convertible
-Mac Cold Air Intake
-K&N Cone Filter
-9mm FMS Spark Plug Wires
-Hedmann Headers 2.5" O/R H-Pipe
-Flowmaster 40 series 2.5" Catback