I had a Carbonio on my old AGU 1.8T and it sounded mental. Imagine Darth Vader with a throat infection. The 'dump' noise, as you put it, is louder due to the sound being able to escape through the exposed filter (stock airbox is a closed unit) so you'll be grinin' from ear to ear with the noise.ok saying this witout being a chav but NikB would it be heard quite well outside the car?
The valve is an ecotek valve, it works via the brake servo pipe, yousonny what is this valve you speak of ?! The harder you drive the better the MPG ?!?! 
How does this valve work, where does it go ect??
Are the expensive, as all good things are