I have a 2000 mercury cougar with the 2.5 litre v6 auto i would like to go with a 5 speed with a bigger motor,how do i find out what will fit into this car without much problems?  

That sort of project would be better answered by a Ford head. Not to sound mean or condescending or any thing, but this is a forum for japanese imports. The occasional chevy and neon lover will get some advice due to the type of project that they want but, Fords will be Fords and if you want to build one thats all good.
I'm only going to hint at some thing that you could do to your engine... TURBO! Build it up with some of Fords motorsport replacement stuff or build up a 3.8L duratech engine and supercharge it. Options are limited to what Ford offers and there isn't that much of a market for building up a cougar, that I know of. Google aroud and see what you can get and go from there,Good luck.  

That sort of project would be better answered by a Ford head. Not to sound mean or condescending or any thing, but this is a forum for japanese imports. The occasional chevy and neon lover will get some advice due to the type of project that they want but, Fords will be Fords and if you want to build one thats all good.
I'm only going to hint at some thing that you could do to your engine... TURBO! Build it up with some of Fords motorsport replacement stuff or build up a 3.8L duratech engine and supercharge it. Options are limited to what Ford offers and there isn't that much of a market for building up a cougar, that I know of. Google around and see what you can get and go from there,Good luck.