Yes, I have that setup and think it is great. Install of any dp on the MS3 is a b****. If you are not very handy with tools, have access to a good lift, have all the necessary extentions and wigglers to get into the tight places, you probably should have a good performance shop do it. If you are impatient or not careful, you can strip out the turbo studs or damage the oxygen sensors.
There are threads here on this. Believe, me, however, that if you take your time, read the how-to's carefully, have the right tools and equipment, or if you get a good shop to do it that knows what they are doing, the rewards are well worth it.
With CAI and the stealth back and one step colder plugs, my quarter mile times and 0-100 mph times have dropped dramatically. You will need to watch boost level and need either a boost gauge or Dash Hawk or an AP or some type of monitor, because there can be a tendency to run a couple pounds higher boost, or to get unacceptable boost creep. This might cause occasional fuel cut, but it has been very rare for me. You should notice that you spool up quicker, get on boost easier and maintain steady boost at max factory levels much easier.
The positive benefits, IMHO are most noticable in making the power band broader in that it seems to not only produce more peak power, but the power comes one earlier, fattening up the power curve, especially when under higher engine loads like out on the highway in 5th and 6th gear.
It does not raise your maximum power rpm. It does not extend the power curve out further to the right, past 5,500-6,000. The limitation there is the small turbo's thermal effeciency limits.
It does allow you to hear the turbo whine. Exhaust will be noticably louder. Some like that. I ended up putting a very effecient, high flow reso in the middle of the RP section to tame the drone and lower the volume.
