yamaha prop size??????

[kbkindle]

i have a 2004 yamaha 200 hpdi[small block] engine on a ranger 195 vs.having trouble with slippage or running out of water an a long curve at wot motor second hole from top. no jack plate. they tell me to change props? ihave a yamaha prop 25m they say go to a yamaha prop 25t-i does any know what the difference in size and pitch i assume there both 25 pitch. kbkindle