The roads in Detroit are so bad your tires are only contacting the road
surface intermittantly between potholes.  Locking them up while airborne
between holes should be no problem.
    Stock vanagon brakes are meant for a fully loaded commercial vehicle.
My Westy has had 4 hanggliders, 1 paraglider, and 5 fully beer gut grown men
go up and down mountains all day looking for good flying conditions.  I
probably went up and down 6 mountains in one day.  I did trash my clutch
that day, but my brakes never faded.  It is not a Ferrari, but the stock
brakes, properly maintained, are more than adaquate.
    A couple of years later, my brakes were worn, my rotors were  warped (I
wonder why), and I had to spend some bucks.  New rotors and pads cost 60% of
what Gowesty was charging for SA brakes.  SA brakes came with new bearings
and new calipers (over 130 each for stock calipers).  It was an easy choice.
 The SA brakes would save me money long term.  Smallcars kit would also save
most people money long term.
    My SA brakes do seem a bit better than stock, but I don't test them that
often. I put them on because I was cheap.  For 600 bucks, I got new rotors,
calipers, pads, and wheel bearings.  I did a brake job once, instead of
potentially 3 times.
    If Smallcars kit includes everything it is a bargain.  Do it once and do
it right. Or, you can save a few dollars, and piece together a system, and
then a year later put on new wheel bearings, and then rebuild or replace an
old caliper or 2.  Imagine doing it in West Texas, or the NWT of Canada, and
you will be cursing your choice to "save a few dollars".

87 Westy (now SVX, SA brakes)
91 Vanagon GL (soon to be 2.5 Subaru, fairly new stock brakes and happy)