The results of a new air filter and GTA mod.
It is all done and mounted properly now. The GTA intake pipe was a a doddle to get in but fiddly to secure. The old 2.0 TS resonator needed to be cut in half to remove it, which was nice. I have a very lightly oiled pipercross air filter in the original housing.
My findings so far.
The GTA pipe does add a little noise, but not a lot at all. You have to have the windows down and the stereo off to notice any difference. The fuel economy is exactly the same as before and the main air box now wobbles about a bit! The old resonator held it more firmly than the GTA pipe. I would suggest that the GTA mod pipe and the pipercross air filter combo don't add any more power, offer any better drivability or have any real benefits. The trumpet in the air box makes more of a difference to both noise and responsiveness. It would appear that with it in place, the noise is quieter, and the power better low down. Without the trumpet, the intake noise is louder and the high end power is better. All observations are subjective of course.