Here's a graph I made a few days ago showing how this turbo holds boost way up top. This is a *rough* tune, so its a little choppy and has a few low spots. This is a basic 3rd gear pull...sometimes on my IX turbo I could hold boost pretty good up top in 4th gear, but not like this thing! I've logged 24.7psi @7800rpm.
The spool area is a little lacking, I switched some settings in my bcs stuff that cuts down max upward correction based on TPS, and the net result is less WGDC during spool-up. I'm trying to figure out a way around it, as it induces a bit of lag, yet the turbo flows more than the stocker so while driving it, you really don't notice.
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More info, just a general update:
I've put about 300 miles on the car (it is my daily driver) since putting the turbo in, and after getting boost dialed in, I have been having nothing but fun with it. It's natural to want to shift as power peaks and falls off. On the stock turbo it happens around 6000 and then shift at 7000. With the BBK, 7800rpms is there before you notice and its time to shift! I have GSC Beehive springs w/ kelford 272 cams and have an 8300rpm rev limit, but I try and shift before 8k to keep the bottom end happy for a long time to come.
Cruising and part throttle, the car actually feels more responsive than the stock turbo. I'm sure part of this is tuning, but the car def feels more torquey under daily non-WOT driving. At 70mph on the freeway, top gear, I can step on it and roll back the throttle a bit and get plenty of passing momentum, it is just so close to the stock turbo it is amazing.
Lastly, the week before I installed the BBK I had been taking care of my brother's dog, Mack. Mack is a pointer/lab mix and 80 pounds or so of spaz-tastic energy bursts. I strained my shoulder/neck a little in the mix of things, and then doing a turbo install, my neck was less than happy but I wasn't really in pain. Well, the BBK did NOT help things, my neck felt WAY worse monday and tuesday....ironically i was doing pull after pull after pull doing street tuning Weds was bad and today I've been taking it easy and it finally is starting to feel better. So yea, hang on tight, cause this turbo means business!