I heard once that Team Shelby would double up the firewall of their race cars to add stiffness.
This is a great solution!
Bravo!
I know on the Shelby Mustangs the Export brace and additional tower to tower brace made a big difference in handling and those cars were double wishbone front suspension, I can only imagine how much a good brace would help with the MacPherson struts. Here is what was on my 1966 GT350, the ribbed angled brace is the "export" brace rather than the stamped sheet metal left and right side of the stock US spec Mustang. the bar in front of the engine was called a "Monte Carlo bar" and dates to the Monte Carlo rally Falcons and Comets. That one was specially made to clear the dual Holley 4 barrels.
On the Mustangs, the pinch weld between the firewall and cowl is right where the four bolts across the back go, on our cars that area has no structure, it is just a sheet metal barrier. I would imagine it could be reinforced with some angle and probably braced across to the inner cowl (I would only try that with the windshield out), this would give a strong enough area to brace too, but it would need to be removable in order to do much on the engine.
A side to side strut brace ...could feel the difference on my GLHS and the K-wagon.
Great stuff for great cars! Poly engine mounts and bushings at: http://www.polybushings.com
Maybe I need to find one of those for my konvertible.
A 3 point strut tower brace helps an immense amount with cowl shake on foxbody cars. I'm assuming it would do the same on k cars, but on foxbody cars there's a pinch weld that runs across the firewall. You would probably have to do a reinforcement plate to where it would mount to the firewall.