what is the difference between the upgrade handling kit from gmpartsdirect:
http://www.gmpartsdirect.com/results.cfm?singlepart=1&partnumber=pk12456148

and the kit from zzperformance:
http://www.zzperformance.com/grand_prix/products1.php?id=571&catid=138

there is an extra bar in the first link that is not present in the zzp link. is that an unnecessary piece? that's quite a difference in price ~$80. i will assume that the one from gmpartsdirect will do more for handling than the one from zzp. i just want to know the difference.