There are loads of threads to find this info in, with input from a lot of experienced focus owners, who probably won't want to post the same thing over and over again.
Exhaust system and manifold, Decent filter and cold air feed and maybe a larger throttle body and good remap, seems to be the conclusion, but this has been talked about quite a bit and opinions vary a little, so I'd say you need to find some of the past threads.
As for the pipe; I'm guessing you mean between the filter and throttle body, and you can get s/s pipes from most aftermarket retailers (try deamon tweaks, burton power, etc) , but you'll have to find the measurements neccessary to order the pipe.