r_decal_cover_count "4"
r_decal_cullsize "1"
r_decal_overlap_area "0.4"
r_decal_overlap_count "3"
r_decals "200"
r_decalstaticprops "1"
mp_decals "200"
The max amount of decals are 200 (change r_decals and mp_decals if you want to go higher), put these into a autoexec.cfg or put these manually into the console once but I'd rather put them into the autoexec.cfg to make sure it doesn't reset for some reason.
Make sure that r_drawbatchdecals is set to 0 aswell