I've seen some articles on freshalloy and they linked an SAE documentation... I can see it being beneficial in noise suppression (i.e. a luxury car application), but I'm still unconvinced about chassis stiffening. Why isn't my E46 M3 stuffed with the shit? BMW put all sorts of other chassis stiffening crap all over it... it has braces all down the transmission tunnel, across the rear diff, strut tower braces, etc. But I don't think it has chassis foam (I've never cut my frame rails open, but I'm pretty sure they're hollow)...

I just have a hard time believing reviews of all the chassis stiffening products I've read about on the internet. People "claim" that all sorts of things make HUGE differences in chassis performance because they're looking for justification for spending the money on shit like strut tower braces and fender braces and all the other crap they sell for cars.

I'm pretty sure that if you didn't tell people what was changed that they couldn't tell the difference between a car with strut tower bars and one without. Same goes for the majority of the little braces and shit they make.

What you're saying is if you took two identically equipped 240sx's. Both with the same suspension mods, the ONLY difference being the chassis foam. And you had someone drive them back to back, the driver would be able to tell easily which one was foamed? If so, that's a pretty remarkable claim!