For me 100mg of harmala extract is not causing any nausea. 150mg already is and 200mg causes severe vomiting. At 100mg it is not much psychoactive, at 150mg it already is, at 200 it starts to be very active.
It all depends on whether the desire is almost pure dmt, mix of harmala/dmt, or mainly harmala experience. These experiences are different.
Not only harmala extract is causing the nausea, dmt as well. Not for everyone, but for a lot of people it is.
100mg of harmala extract seems to be perferct dose (for me), because it inhibits MAO quite significanly and is not yet very psychoactive. There is a need for higher dose of dmt with such low dose of harmalas though. Everyone can find his sweet pot for harmalas first (before it starts to cause a nausea) and once he has it, he can add the dmt.
Harmala extract is not good for rectal ROA. It is difficult to keep it inside.
Oral dmt usually requires at least 3x higher dose than rectal. Yes, it is noticeably longer acting, but the shorter duration of rectal ROA is often a benefit, allowing the use within working days, not just the weekend.