High volume and high pressure
are two different things. When what Auto10x says happens, there has to be an opening in the system so large that the pump can't build pressure, or only partial pressure, which is another problem altogether. In a normal engine, a high volume pump will produce as much pressure as the spring in it allows, unless, as in dsmith's case, something is wrong in the pump. A high volume pump will pump more volume, as may be needed with more bearing clearance, rod side clearance, etc, but as previously mentioned, will normally only pump as much pressure as the spring allows. High pressure springs, such as those used originally in side oilers, are available, and can be added to a high volume pump if that is what you wish. As for blowing out
oil filters when using a high pressure spring (not in dsmith's case, as he has another problem), use the Fram HP 1 filter or equivalent; it's built to take the extra pressure. Even the neoprene seal at the top of the filter is thicker & relieved into the filter to prevent blowout. Sadly, to my knowledge, it doesn't filter any better than a standard Fram unit.