Pseudo-code for conditional piping

if-piper.js

var feed = 'http://somefeed.com/rss'
var req = request(feed)
req.on('response', function (response) {
  if (sometest(feed)) {
    req.pipe(iconv).pipe(parser)
  }
  else {
    req.pipe(parser)
  }
})

The condition could also be something like, response.statusCode === 200.