You need a locking tremolo (floyd) As you pick the last string 6th E or B for seven string then slowly push down the bar all the way down until it flutter
Actually i prefer calling the shredding sound the "vroom vroom" sound. U know when u play a fast lick with only the first 3 strings. 3 5 7 3 5 7 somethin like tht. Haha..it sounds like vroom vroom to me. On neck pup.
I was at the Marine Cove jazz thing where one guitarist made a pretty lousy tone setting on his distortion, and when he did pick scrapes on the bassstrings, that sounded like a motorbike starting up. And died.
Can try twiddling around with your distortion for a bad tone, do some weird strokes with your pick, and you might get that bike sound. Good or bad ones, I dunno though....