Haha bro, ECA (E for EPHEDRINE HCL) is NOT natural. It is banned by all natural bodybuilding organizations and I'm pretty sure it's illegal in all natural bodybuilding competitions except MuscleMania. Now, Ephedrine alkaloids, through Ephedra/Ma Huang is another story.
As far as "not getting disqualified" There are tons of things you can take that will not show up on the tests. GH, IGF-1, Even Clen+DNP and many other fat-loss or anabolic peptides/drugs will not necesarily show up on a test.
But that does not mean it is not cheating.
And as for the guy above me... LOL bromo is about as un-natty as it gets.
Stick to caffeine, Synephrine, Octopamine, 5-HTP and Yohimbine products. Typically OTC is still "natty"