Collapsing US bumpers: safe?

[ggehrke at gmail.com (GGehrke)]

I'm thinking of collapsing my big ugly US bumpers, but I'm curious
what sort of crash protection they actually do provide.  Does anyone
know what the official spec is (i.e. were they designed to resist a
10mph hit or something to that effect) or what consequence there would
be to having the shocks emptied?
At this point I'm not terribly concerned with doing it for it's
aesthetic value because the car's pretty rough looking anyways, but I
have them off for powerwashing and repairing a bit of rust, so I'm
thinking I might as well.  The car looks so good without any bumpers
on it, too.  If it's genuinely unsafe I'd rather just keep them as is
for now, though.

Oh, and I just finished power washing the car.  Did a real bang up job
on the paint. Flaked right off all over the place.  Now the car's
literally about 6 different colours.  It was intentional, but ugh.

Other recent projects:
My headlights died and I couldnt find the problem (sockets fine,
switch fine, fuse fine, etc etc) so I just wired them up with heavy
gauge wire to toggle switches on the dash.
New cable from battery to starter and ground strap to hopefully fix
other electrical gremlins and starting problems.  It does actually
seem to run much better!  It starts without me having to give it any
gas and idles more smoothly.
Painted my dash black to fix scuffs and petrified duct tape residue from the PO.
Seafoam!  Timbo was right, fun smokescreen!  This helped reveal, too,
though, that my entire exhaust system is shot.  Smoke poured not only
out the tailpipe but exited at various other locations down the whole
length.
Vacuum and febreeze the interior.

Plus I helped my buddy cut his M3's exhaust in half, gut the cat and
weld it back together.  That was pretty fun too :)

-Grant-