getting rid of whites spectrum xlt

ok I bought this xlt some time ago to do some detecting, it works great on coin and relics but my treasure hunting hobby turned more into a gold prospecting hobby. Really love prospecting bought gppa membership several pans, highbanker, all the goodies but this metal detector just doesnt have a low enough frequency to do what i want. Can I buy a coil to improve this on the xlt or should i just get another detector for gold?

was thinking about a gold bug 2, minelab eurkea gold something in the $500-800 range specific to gold prospecting. I want a detector that will pick up a pinhead at 5 inches or better in heavy mineralized soil. whats my best bet for my price range?

My MXT and Gold Bug are in that range and seem to do fine...The MXT is nice because it can be used for coins/relics also....