Can I add blocking oligos to prevent the second strand synthesis of high abundant RNAs?

Yes. Blocking oligos can be added during second strand synthesis together with TS buffer. We recommend a final concentration of 10 – 100 nM of the blocking oligos during the second strand synthesis. Ideally, those blocking oligos should bind close to the 3' end on the transcript that should be blocked, this way exponential amplification of those highly abundant transcripts during the PCR is rendered impossible.