@Rat80y The drain bolt stretching is a common thing on the DTR, IMO it's a design feature as if you overtighten it it usually snaps. Whilst being a right PITA to get the clutch cover off and wind out the broken part, it does mean the thread in the crankcase is saved (new crankcases = much more difficult/expensive than taking off an engine cover) so I hope you've ordered genuine from Fowlers (get a load of copper washers as well for future gearbox oil changes). Tightening torque is 15Nm so it's also well worth getting yourself a 1/4" drive torque wrench like this one:
https://planetx.co.uk/products/jobsworth-pro-torque-wrench-set-1
There is some truth in both your AI source and what your friend said. In the days of the 12bhp learner restriction, DTRs with the powervalve pinned shut would struggle to rev beyond 6k rpm but properly set up/derestricted/full power it should rev to around 10k.
