What did you do for chassis stiffening?

I have done both store bought and home made frame connectors. Both very worthwhile. You can tell the difference the first time you close the door. I put a set of US Cartools connectors under my 64 Barracuda and made a set from rectangular tubing for my buddies 65 Barracuda. I like the look of the USCartools connectors but I think if you rode in them both blindfolded you could not differentiate the ride of one versus the other. Then I made front and rear torque boxes for mine. They provided additional rigidity but it wasn't as noticable of a difference as frame connectors. I haven't installed torque boxes on my buddies car yet and I' m pretty sure that most any passenger could notice the difference between our cars and am almost positive a driver would immediately notice the reduced flex of my car with torque boxes. The cars have identical suspension updates and very similar wheels and tires.