I've seen allen head bolts with serrated edges under the head,that bites into the metal and acts as a lockwasher--muffle clamp nuts also have the same thing..but even with no knurl,if they are torqued properly and re-checked after awhile,they should stay tight without locktite or any other means..
Do the nini starters have an angled brace to go to the block like oem starters do ?...I'd think with all that more grunt they would want it braced too,not just rely on 2 bolts...