Do NOT fill a PCP above the manufacturer's MSWP.... While it will undoubtedly be OK once or twice (after all, it will have been tested to significantly higher).... you are increasing the effect of metal fatigue every time you fill it, because the metal stretches a tiny amount.... This repeated stretching reduces the strength of the metal every time you do it, and this metal fatigue is particularly bad on aluminum.... Filling above the MSWP decreases the service life, and the more you exceed that (in this case 2900 psi), the shorter the life of the tube before it fails catastrophically.... Such a failure could be fatal.... There may be other factors as Jason mentioned that could fail before the tube as well.... Just don't overfill....Bob
Even if it were true that the reservoir can safely handle higher pressure, and that they arrived at the rating based on some other factor such as the valve retention, there is still the potential that the regulator may someday fail and pass the full reservoir pressure to the valve and cause a dangerous situation.