If your car is a 2000, 2001, or 2002 model year, then no mods are necessary, and the new top and frame can just be bolted on and work fine. That's how it worked for my 01. For model years 97-99, you will need some mods. See below link for the full details. If I couldn't get my hands on an OEM 03-04 top, I would have gone with the GAHH aftermarket top with glass.
https://sites.google.com/site/mikefocke2/installinga%2703-%2704glasstopandframeona%2797
I have an 03 top and frame on mine, and it is awesome not having the cheap plastic back there which really doesn't belong on a Porsche IMO.
