Im still of the view that the engine was designed as a closed-loop recirculating system for a reason, so not willing to dump any boost to atmosphere personally, things are designed as such for a good reason (performance as well as turbo longevity and Im also aware of cost effectiveness) You dont want to be dumping too much boost and risk turbo-stall
Having said that Ive seen no data to prove (or disprove) that train of thought.
Seems to be two groups on here, people who dont want the noise they make and chavs... (Im only kidding, I have my collar up in that picture and Im from Pompey!)
Untill anyone can prove thier detremental the only reason not to fit one in my book is they do make you sound like an R5 GTT or like the Number 72 Bus using its air-brakes...
Personally Im sticking with my 007P. For more of a tissh you can always go for a modified induction system and fitting the 007P 'Reversed' as a few people on here do