More noise, no measurable gain.....the camshaft timing and lift combination is such that the intake and exaust dimensions exceed the flow needs of the engine.
The cam profiles are geared around low end torque.....that's why you feel the power drop off as rpm increases.....nothing to do with pre or post port flow requirements.
Usually any increase in sound provides more of a placebo effect......sounds faster so it must be.
Keep in mind, a 1.8 is only a around 107 cubic inches......same as a Gold Wing motorcycle and more than 3 times the weight to haul around.
The 'go fast' market has never really supported the 1.8. It is considered a base engine that would not appeal to the enthusiest market so it is generally ignored.
The 1.4t version has a bit more support, but the realities are these are econocars and the majority of buyers chose them for that economy.
Enthusiests currently are more drawn towards the high output Focus and Fiesta's as well as certain Honda Civics in the front drive performance arena.
Not trying to pee on anyones wheaties here, just stating fact.