Online - GT5 had 2 distinct different physics, which changed around update 2.07 or 8, so depending on whether your setup is before or after that, will have an impact on how well it now behaves.
You also have to consider that some individual parts of a setup also changed (the affects of which were reversed) in GT5 too.
Knowing what worked when and what changed when is the key of knowing what (from GT5) will work now...