Sub-frame connectors... Please build them correctly!
Most everyone is familiar with body damage caused by severe twist. It was very apparent on the '68 Charger R/T that we'd bought. The rear quarter was ripped next to the door seam on the left side and the right side sail panel had a noticeable dip in it. After replacing the quarters we decided to purchase subframe connectors from U.S.Cartool. Those are the ones that we will weld the entire length and are fitted to the floor. The car will be running a blown 512 stroker and a 4-speed.
On my '67 Barracuda I fabbed my own connectors that are welded front and rear but unattached to the floor. The 408 puts out over 500 horse in front of a 727. I didn't want to tear out my entire interior at the time I did the 'Cuda and figured the amount of stress created by torque would not require as much reinforcing. I also figured that the shorter wheelbase would be less prone to twist. I can't speak of how the Charger feels to drive because it's not completed yet. - But the difference is fairly dramatic after adding the connectors on the Barracuda. The car handles better, feels more solid, and has less squeaks. So my conclusions are that:
1) subframe connectors are a definite benefit - even for general street driving.
2) the amount of strength needing to be added may need to be increased as more torque is being produced.
3) there is a benefit from connectors that may be adequate (on some cars) even if they aren't attached to the floorboards.
