I do agree that the double and triple stacked products are pretty retarded, I do more bridges than stacks myself... but enough people have stacked just about all of them together to know about what to expect. No synergy is capable of producing some huge multiplicative effect... It's really more like the sum... The synergy comes from being able to run the sweet spot on each compound.
20 Epi, 12 SD and 60 tren isn't so bad, it's enough to make gains off each but none is run high enough to give much sides. So the main sides will be shutdown as the sum of the three... you probably wouldn't get many other sides from those doses, and can still make good gains.
When i stacked SD & PP i got less sides than running either because I kept SD at 20 (30 causes backpumps a lot more) and PP at 30 (40+ has higher rate of backpumps & chance at nipple soreness). Interestingly enough, when combined i didn't get a single backpump... And no taurine.
(Maybe sides would have hit me if i ran it longer, but i didn't. )