Sorry, I have not used it so I cannot actually give you the answer you are looking for, but do have a couple of thoughts to share, and felt it was OK to post since no one else had anything to say
Decapeptyl (Triptorelin Acetate) is a GnRH analog. Its action is that of endogenous GnRH released by he hypothalamus which stimulates the Pituitary gonadotrophs to release both LH and FSH.
Given this info, the action of decapeptyl that would be of significance, would be the raised LH, which would, ofcourse, agonise the Leydig Cells in the Testes to produce more Test... This is something people are achieving already via HCG, which is actually an LH mimetic that is "one step" down in the chain of action between these 2 compounds.
HCG already provides the direct stimulatory action of LH, as opposed to Triptorelin, which needs to take action farther upstream on the Pituitary. Negative feedback/Suppression of HPTA would still play a role with both compounds.
I guess you could probably make a very rough analogy regarding Decapeptyl and HCG. Decapeptyl would be more like CJC/GHRH having action on the Pituitary, and HCG would be more like GH with this respect...
Now, as far as a doping test goes, that is a different story I am not sure of.
Take Care.