right, this is the deal.
The 007P is a closed loop valve (recirculating) like the OE valve. This gives less lag as it keeps the turbo spinning in the same way as an atmospheric (vents to air) valve but also puts the air back to the turbo intake pipe meaning less air loss and it helps keep the compressor spinning with the jet of air back into the turbo intake pipe. Less turbo lag resulting but very little sound unless you have an induction kit!
The turbo smart and split R vent part to atmosphere and part recirculating meaning more air loss and less jet of air into the turbo intake pipe so more lag. You can not adjust the valve for a louder sound as this is determined by the size, shape, and position of the atmospheric opening etc. This valve can become dirty overtime and stick open causing power loss. A good clean with WD40 worked on my Split-R when my Colt CZT lost power.
If either Recirculating only (007P) or the Split R/Turbosmart are not set up right - Too stiff (Turbo, intake manifold damage or detonation due to high pressure) or too slack (power loss due to the valve opening when on full boost instead of on lifting off accelerator when pressure builds up to high levels).
Depends on what your after.
-If you can handle a bit more lag and want the sound then go for a split recirculation and atmospheric valve, set it up right and you won't damage your turbo or loose any power at all.
-If you want it to run the same or have slightly less lag a high capacity recirculation valve like the 007P will give you exactly that but not much sound at all, unless fitted along with an induction kit, even then you'll struggle to hear it (compared to a split recirculation/atmospheric valve).
An atmospheric only valve is no use for newer cars as they require an amount of recirculation to keep the ECU happy. An atmospheric valve was an addition to an older car in conjunction with the wastegate (the valve that diverts exhaust gas around the turbo when you lift off the loud pedal).
Hope this helps!