I use the high pressure hose but from maximum distance - I never use the brushes because 4wd owners have a tendency to scrub mud off with those brushes and not rinse them - that aside, the brushhairs are rather coarse and can scratch the better paintjobs out there...
in either case, i've found that elbow grease of some sort is required...
i use the pre-soak at dazzlers, wipe it down with a chammois to get rid of the brake dust, exhaust dust and assorted grit
then the soapy high pressure hose, and use a flannel with either some degreaser or bam to get rid of the stuff that is stuck to the paint... then i rinse it down, apply a hot wax and then rinse it off with the spot free finish
its very frustrating when your paint flakes (and it can happen with a hand wash too) but from what I've read, most japanese based resprays are done on the cheap because the owner is simply trying to get rid of the car
-D