There are people who swear by aftermarket weatherstripping and many who' have
had a bad experience. :L
If money is no object, purchase the GM weatherstripping. The cost is usually at least
double what the aftermarket weatherstripping costs. Some people have mentioned GM now
imports the factory weatherstipping and the durability is no longer there. I've
never heard about the fit being a problem.
The OEM was a latex type weatherstripping which is soft and conforms to different shapes
when compressed. Most of the aftermarket is a type of rubber that is very stiff.
There are after market companies offering a latex type weatherstripping so
if you go aftermarket get latex.
Because the rubber type weatherstripping is stiff you have to slam the doors or hatch to get them to shut. Same with the A and B pillar weatherstrips, the first time you have to sit on the top to get the top bolted down. People have also reported problems getting the windows to seal even after trying to adjust the glass.
Eventually the top gets easier to install but it can require some extra effort.
If the top you have stress cracks in is the acrylic type the stress cracks are usually
only in the top layer coating. You can sand the top layer off and have a clear coat
sprayed over it or leave it as is and polish it every so often. If the top is the fiberglass
one the stress cracking is not normal and probably the top is not adjusted correctly.
Here's a link on how to adjust the top.
http://www.melroset-tops.com/tech/C4_Roof_installation_procedure.pdf
