Hi Greecer3,
I can highly recommend the REVO 52. It is hands down the best fitting engine for the Top Flite P-51. I have numerous pictures and posts on other threads here. Here are the links. I also have a few links to youtube. You will see that it flys great and does not lack power.
http://www.rcuniverse.com/forum/m_45...59/key_/tm.htm
I start at post 1454
http://www.rcuniverse.com/forum/m_45...61/key_/tm.htm
I start at post 1513
http://www.youtube.com/watch?v=0Z2hgiar9sA
I start at the 3:09 minute mark
http://www.youtube.com/watch?v=dpUwg...eature=related
Hope this helps.
Karl