Take a look at bombshell decals. The really look good. Haven't gotten any for my self yet...however, I will soon. Might be building some number of B-25s in the near future after looking at these sheets. it all depends on what version you are building. Here's the link for Bombshell Decals...in case you are building a B-25J glass nose.
http://www.bombshelldecals.com/
Superscale has a few sheets for verious B-25 outfits. Zots as an awesome sheets for later b-25s but I think that sheet is becoming hard to next to impossible to find these days. Anyway hope this helps.