Just skip the pres grp. As an instructor looking at a log its easy to tell who is using a computer. I dive a shearwater petrel, if im with in 3min of an ndl and not on ascent it will go into deco mode. Freaked out my course director. But none the less the algorithms used give so much credit for a true profile the rdp is not able to acurately match it. Also look to see what algo your computer uses and see what gradient factor is set. I use a conservative gradient on the buhlmann z hl 16 algorithm. Also some computers can be set to follow the rdp almost to the letter. Hence the normal disclaimer to read the comps manual!