Flightplans.txt size limits?

Greetings--I'm new to this forum, but given the volume and the bounty of knowledge and experience that I've seen reflected within it thus far, I am certain that this issue has come up previously, and that some of you folks have encountered it. I've not been able to find a clear answer/solution up to now. My flightplans.text file has just over 20,000 plans stored in it now (the original was replaced with a combination of extensive third party plans (among them PAI, and Most Realistic). Its size is now just under 16MB. I've found, however, that I cannot paste more than a few more plans into it; when I tried to do so with Most Realistic's US Airways plans, only a fraction of them were added before they were "cut off," so to speak, in the middle of one of the flight plans, as if the size limit of the file (I didn't realize that there was one) had been reached. I've tried this several times, in both Wordpad and Notepad, with no luck. Is there a set capacity limit, under the parameters of these utilities, that allows only a certain number of flightplans? Is anyone aware of a way around it? I'm aware that some of you have 250+ aircraft in their aircraft.txtlists (I got to 143 before I ran into this wall). How many flight plans have you other folks been able to shoehorn in?Thanks!!!!:-zhelp