noise difference - very little. Maybe every so slightly louder due to venting slightly larger amount(bigger body) mine you can hear alot more of the turbo noises now anyways due to the samco hoses.
performance - no difference.
most noticable difference - smoother gear changes. Yes you read that right, no mechanical conection, but does make gear changes smoother...
Reasons:
1.It was a GB, so got a discount.
2. Serviceable at my leisure. Any hint, it might be sticking, or passing, i can service it with 3 orings, and some grease.
3. Metal, over crappy plastic. (Feel how hot your DV hets standard. Guess what it might be liked remapped..
4. It is a piston valve, unlike the bosch Diaphragm valve.
harder wearing, and i didnt like the Forge Diaphragm valves either as i had seen them fail. (Forge do pistons too, but i judt didnt fancy one at their increased cost at the time compared to the amd equivalent)
5. along with servicing/checking , as and when you please you can also shim it, or change the springs to change the charistics of how it opens and shuts.
I run a 3mm spacer or shim in mine. It keeps the DV shut longer and firmer, and when it does shut, it shuts it quicker hence keeps boost on that little bit more, by making the sping tension tighter