The main advantage of a dump valve is to wind up people at bus stops(especially cruel if it's raining).I love it:-)

 

I had a Turbosmart Veeport VTA on my previous WRX MY03. The best bit about it was when I took it off after 3 months when it started getting on my nerves. The most noticable performance improvement was at this point i.e. back to factory spec recirc valve. It now resides in its original box, all shiny and blue, on my bookshelf and COULD BE YOURS if you PM me with a reasonable offer!!!!!!