RE: Parkzone RTF P51-D brushless upgrade
Pros: It will fly soooo much better.
Cons: It will cost more.
If you go with a [link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=EFLM1000]Park 370[/link] inrunner and use the existing gear box and a [link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=THP13503SJPL2]Thunder Power 1350[/link] Mah 3 cell LiPo and about a [link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=AGNE25G]25 amp[/link] speed control it will be a decent set up. Of course you will then need a good [link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=THP610]LiPo charger[/link].
If you add all this up after getting it all and two batteries you will spend about $314