GHRP's simply activate the anterior pituitary gland causing the door to open if you like, I don't believe it stimulates the gland to produce more GH, but in theory if its emptying I suppose it would try to make more? The hypothalamus stimulates the gland normally, when we wake and sleep etc according to our sleep patterns.
If you use MOD GRF or CJC DAC, then you are actually taking the first section of the GH chain, this section from 1-29 is the part responsible for cellar repair, so the bit that makes us grow. Of course you can just use products that are further down the pathway.
GH becomes MGF eventually, you can buy these splices and variants, MGF has to be used locally as it cannot travel the blood stream. Pegylated MGF however can, then you have IGF-1 DES, very anabolic, locally used, then IGF-1 LR3, can travel the bloodstream, these are not GHRP's.
Highly recommend IGF-1 LR3 and PEG MGF. However CJC DAC used correctly is awesome, but head aches have been reported, but then we get head aches anyway dont we, and when we are on a drug we blame the drug!
CJC DAC 7 day half life, so, take 4mg the first week, then the next 11 weeks take 2mg, this will keep your system topped up to 4mg on average for 12 weeks, then a break should be taken.