Having reminded Luis early on of a "feature" of the design and I will go no further and having had hands on "tutoring" from Luis, I would suggest that reading the link Bryan provided concerning the volcano orifice adjustment and waiting for Luis to provide a little more on the HPR Venturi adjustment would be wise.
The ability to approach animals so close is a huge benefit to dh regs and is not to be understated. There is a learning curve as well to getting best performance. The short video I posted somewhere it is not completely obvious, but I swim through the water at a slight angle, my body rolled ever so slightly. I do not use a flutter kick but instead a scissor and an odd frog kick combination that moves me efficiently and allows my slight body roll, which to me is natural. I frog kick as my body rolls level exhaling and a larger scissor (like a side stroke) as I roll slightly along my axis (either direction) and inhale. As a swimmer I am accustomed to rolling to breath and I time my breaths to coincide. We all have our tricks and that is mine, thus my often saying, I am not much into the very low tanks because I roll my body for inhalation and generally long and slow inhalations and exhalations are very efficient for me. YRMV. And BTW, I use the same swim technique, double or single hose, though it has advantages with dh that are not applicable to sh, the swimming method is efficient and makes good speed when needed and that is always applicable.
James