Founders Performance 251020B - GM F-Body Round Tube Subframe Connectors - Weld-In Black - Car Set Founders Performance Round Tube Subframe Connectors Firebird Hardtop First thing that should be done to stiffen up the chassis and allow the suspension to work properly is the installation of subframe connectors! Subframe Connectors assist in maintaining the overall integrity and longevity of the vehicle. Take a close look at any unibody car that has been run hard. The doors don't close quite right and the alignment shop has trouble getting the car to drive straight. If you want your car to remain rattle free and you want to get the most out of other chassis and engine mods, you have to connect the front and rear frame sections with something stronger than sheet metal.