Know Your Roots

It's probably worth mentioning that D.R.I. and Suicidal Tendencies started out playing punk shows and appearing on punk comps and later crossed over into playing a more metal style. The second half of the 80s had a fair number of bands that were formerly punk bands shifting to a more metal style. Hardcore punk in general became much more metal influenced at that time, and vice versa. Thrash punk eventually mutated into thrash metal. Earlier 80s comps like New York Thrash were straight up punk comps. (Amusingly New York Thrash has a track by the Beastie Boys from when they were still a punk band, back before the single Cookie Puss lead them to their destiny as rappers. )

Indeed. I have to say I was introduced to DRI as a Thrash Punk band in the late 80s/early 90s by a cousin (a skater, of course) who was heavily into such music. Given that DRI's popular emblem at the time was Thrashman (and I believe the shiny new album at the time was Thrash Area or something - the only song of theirs I personally recall is Beneath the Wheel, but they're largely not my kind of music), it would seem bizarre to say they weren't some form of Thrash.