They appear to be rudimentary braces for the strut towers and firewall, but why didn't they keep them on the production cars?

 

They also dropped the metal tabs on the strut towers that those bars are attaching to after MY05 as well. I tech told me once that the tabs were there for a strut tower brace that was dropped before production started. That sure looks like what he was describing.

 

Interesting! The tabs on my strut towers are barely large enough for the ground wire from the battery. Did the tech say if the braces were necessary/useful?

I have noticed a growing trend of all unibody performance cars having bars/braces up the wazoo. The Nissan 370Z has a triangulated strut tower brace system that bolts to the firewall.

 

my strut tower tabs are pretty big and i have an 06, i bet if the ground strap was not there i could bolt a brace to it, but i would like the see an FRPP brace come factory atleast in the new GTs

 

Seeing as that is a CAD (computer aided drafting) image, and companies frequently use CAD for FEA (finite element analysis). It may be a simple case where those bars represent the engine assembly for structural testing of the chassis flex using MES (mechanical event simulation). I'm usually wrong, but wouldn't it be cool if I were right.

 

Probably a preproduction idea discarded after design development (e.g. did not really need it from a structural integrity standpoint).

 

I may be wrong, but my understanding is that the firewall cowl area is non-structural on our chassis, unlike the previous generations, and anything that would apply a load to it would only create issues, not solve them. This is also why ALL of the aftermarket braces are tower-to-tower only. I also have yet to see any definitive data that suggests the strut-tower brace does anything for rigidity.

 

Back in the day when I was a student at Cal Poly, the dean of our dept had a fairly new 65/66 Mustang. Curious as to the effectiveness of the Shelby tower to tower brace he rigged up a simple device to measure (actually mark) any movement between the two towers. He did some cornering tests (auto cross or something) and then inspected his device and confirmed there was relative movement between the two towers. Don't recall the magnitude, but it was a lot more than 1/16".

You are right, looking at the fire wall for the current Mustang its obvious what ever went into production was not intended to accommodate additional bracing. Does not mean there isn't any movement. The movement for a production car is probably not significant enough for the extra expense to add anything to make it less or none.