Well, after about a 12 hour install, I finally have my new turbo installed. Thought I would report on my opinion, experience so far with an update or two after I have driven with it a little longer. I couldn't really find any "reports" so to speak when I was trying to choose a turbo so I will do the best I can to explain what my experience has been for someone else.
First off, let me start by saying that prior to installing this turbo (along with bellowed up pipes and a non-EBPV pedistal) I was running the factory turbo with the red line to the wastegate disconnected and had been running it like this for a little over a year. Oh yeah, I also chose to go with the 1.15 A/R non-wastegated housing and installed an overboost eliminator.
My initial impression was that something might be wrong, it sounded somewhat like a 03-04 Cobra between 3-10psi (In my defense I was expecting it to be loud, but figured it would be the high-pitched turbo noise I am used to). After a little bit of reassurance from Dirk on here, I got out and played around some. I can see why some people say it is too loud, but I don't mind a loud vehicle as long as it sounds like it is in good mechanical shape. Boost numbers at WOT were quite similar to before the turbo swap....about 27-28psi. I didn't notice any more lag than from the stocker, in fact, from about 10psi to 25psi it seemed to build boost WAY faster. EGT's appeared to be about the same as before the install. The only other thing that I noticed on the initial test drive was that going up one of the hills here at 60mph on cruise it used to downshift out of overdrive accellerate back up to speed, shift back into 4th only to shift back into 3rd one more time before we got to the top. Since installing the GT38R it stays firmly planted in 4th at the same speed and load on cruise. It doesn't even sound like it is working hard anymore. This was the extent of my testing after the install due to having to do the install by myself in my driveway on Saturday and I was pretty tired and beat up.
Fast forward to Monday. On my drive into work I cruise down a divided 4 lane that has a speed limit of 65. Of course everyone runs 70-75 and who am I to get in their way?
With the factory turbo I was running 5-6psi just cruising between 70-75. As I expected the GT38R actually runs LESS boost while cuising, around 3 psi. I expected this with the 1.15 housing, but didn't expect the difference to be so much. I am quite interested to see what happens to my gas mileage with this turbo, between the lower boost while cruising and the apparent increase in power in the midrange (as evidenced by no longer downshifting while going up that hill).
Hopefully this might give some other people contemplating a turbo swap a better idea of what to expect from the GT38R. I personally bought mine as a step towards a 400-450hp goal. I was already border line with 28psi on the stocker and it seemed like a logical next step. So far I am quite happy with my choice (although my wife says that the noise it "annoying".
) I will report back in a few days with any change (or lack of change) in my gas mileage.