I was "in" on XV's engineering. The guy spent BIG (really big) bucks with some Toronto-based engineering outfit to find out what works, what doesn't. I was there during the test sessions (B-body, 2006). The real surprise was the beefing the top of the rad yoke did NOTHING.

This was done on a "4-post" hydraulic table. The Canadian engineering team was online with an English F-1 engineer in the British Midlands. The fun was hearing the Brit's comments on the stock B-body suspension geometry: "Better than a new BMW...."

Photos here:
XV Testing May 2006 Toronto

The sawtooth frame connectors are, of course, somewhat of a compromise. 2X3" tubing, floor slit, is the way to go. But reality: Very few guys would install that. The sawtooth makes an incredible, immediately-noticeable improvement.

The US cartool copies all fit better than the "original" XV stuff. And their service is 10X better. Just installed some recently.

Shock tower braces work, but must be huge and triangulated back to the firewall. Again...reality check.

Rick