In short, the answer is yes. Uusing higher doses of GHRP-2 and Ipam you will result in larger spikes in GH. However, I would NOT increase your dose of ModGRF1-29 (no dac) beyond 100 mcg per inject (150 mcg, max), regardless of how high your GHRP-2 or Ipam does goes. If you are going to increase the dose of anything, your money would be better spent on increasing the dose of GHRP-2 and Ipam, as the effectuiveness of the GHRP's is more dose dependent than ModGRF1-29.
However, I have a better idea. Implement Hexarelin. It is the strongest GHRP available and will blow your GH levels through the roof even when used at only 50 mcg per injection (when combined with 100 mcg Mod). This has been clinically proven (search Pubmed) At 5,000 mcg per vial, you would get 100 freakin' doses out of a single vial. It is far, FAR more coct-effective than Ipam....and works about 10X better at increasing GH levels, even when used at a fraction of the dose.
But...you can't use Hex all the time due to desnesitization issues. This doesn't mean you can't continually use it--it just mans you can't use it too frequently. I would add in Hex at 50-100 mcg (with 100 mcg Mod) 2X daily, but only on Mon/Wed/Fri. During the other times, use GHRP-2 with Mod. This will allow your Gh levesl to rise higher without spending more money...and will alos prevent desensitization from occuring with the Hex.
In my opinion, Ipam is really only suitable for pre-bed use at high dosages, but for most people, they would simply be better poff using only GHRP-2 & Mod and Hex & mod. It will cost less money and result in higher GH levels. You would need to use a very high dose of Ipam in order to equal the increase in GH you would get from a single inject of 250 mcg GHRP-2 & 100 mcg Mod. Yes, Ipam will maintain elevated GH levels for longer, which is good for when you are sleeping, but is it really cost-effective? Not for most people.
As far as prolactin and cortisol goes, it really isn't a big deal. When Hex is dosed at 50 mcg with 100 mcg Mod, there is only a small elevation in those hormones--not enough to cause any issues. The benefits far outweigh the negatives, which are almost non-existent. GHRP-2, even when dosed at 300 mcg per inject, does not cause a large spike in those hormones, either. Basically, you can take these drugs at very effectuve dosages and not have to concern yourself with prolactin or cortisol. Besides, if you use AAS, then cortisol is already being inhibited, which would pretty much negate any increase seen with the GH peptides.
As far as water retention goes, it varries according to the GH peptides being used, as well as dosage. Some GH peps cause more water retention than others. However, increased water retention is also indicative of high GH levels, so this is not necessarily a bad thing. In BP is a concern, take a blood presure supp, like Hawthorne Berry, which is included in IML's Advanced Cycle Support product. I can take multiple AAS that are all known to increase BP and still stay within a normal range when using that product. Others will tell you the same thing.