Hello Gary,
Not all areas of our nation are the best places to hunt, Some areas make detecting difficult regardless of the machine. Here in California some areas are not the best. Most machines coming out of the factory will operate well with some minor adjustment "Sat & delay" for the unit to perform reasonably at most locations, For some areas the unit may need more to help it operate decent. That's were some mods are needed to help the unit perform well in those areas, If the user can apply these mods to his/her detector then unit should operate a little better than before. However, Sometimes when you change the machine to perform well under difficult conditions it will not get maximum deep as before when searching areas that had been friendly to the machine. So! You lose it here and gain it there or vice-versa, Depends what kind of hunting a user wants to do. And kiss the warranty goodbye once you touch the circuit board.
To be honest, I'm not the brightest light bulb in the room. I ask questions from friends and people who know and then apply what I've learned to my detectors. Some ideas are my own and are working well, It's a mater of how much you're willing to push your detector with the expense of maybe ruining the circuit board.
In the Headhunter Pi's case, I did some minor changes to help it operate well in certain areas of California.. Like other detectors, the stock HH PI will operate well in most areas sometimes needing to use the delay a little which is normal for most Pi's.
The mods to my HH Pi's are as follows,
One unit has a faster sat speed to operate when the soil gets tough and is fitted with a special 10.5" center mounted 15 usec coil made by Eric Foster.....
The other has the stock 11" coil and the sat speed in increased as well.
The third is actually a unit I put together from the ground up, It's from this unit I was able to do all testing to learn how to help the HH PI operate in the worst areas which I can now apply to other Pi detectors as well. This unit operates with a stock HH Pi 11" coil, 11" DD GQ coil, both 8" and 11" GQ coil or a mini probe to be used as a probe detector. It also has the SAT speed increased and the DD Mod Reg mentioned on his post above.
The HH PI is a great deep seeking pulse machine, One of the deepest pi detectors on the market.
HH, Paul (Ca)