The intake will make a big difference on a remapped car, but the map has to suit the mods so it's better to do intake before having it mapped or you'll be paying to get it done again.
The Mugen intake is one of the best out there for the FN2 as long as it has a cold air feed like the Mugen intake tract or the Driven Crazy scoop.
The Mugen intake isn't that loud though. It's louder than OEM, but still pretty subtle.
Tegiwa's intake is remarkably similar to the Mugen. Just saying...
The GruppeM is a good intake but does get to its limit when you start doing things like cams, when it can start to be a restriction in the system.
If you can find one second hand they are worth the money, though still more expensive than the Tegiwa intake. New they are on a par in price with the Mugen.