I ran a GT4088R for all of 80KM last fall before I blew a bead from a weld off the mani through it. It was real nice and smooth and quick to respond I felt anyways. I am running a 2jz though.
1 thing I would point out after my experience, which granted was in fact my fault not Garrett's is the cost of repairing a Garrett turbo is nearly the same a buying a brand new one outright.
And after further research I discovered that Turbonetic's (which use a Garrett cartridge anyways) have something on all their turbos call the "No Fault Warranty". After speaking with one of the Turbonetic's guys I was informed by him that I could essentially suck a rabbit through it under the warranty period and they would happily hand me a new or fully repaired one on their dime. Yes even the ball bearing models which of course the 4088r is.
The GT4088R does ship with a restriction fitting on the oil inlet side as well as a huge bright orange tag very loudly expressing how important it is to limit overall oil pressure into the turbo or seal damage will occur. 10AN return line to the pan is perfect and infact what Garrett also included on mine when new.
If I was to buy again new I would most certainly find the BB equivalent Turbonetic's unit rather than buying the Garrett unit. Since they are actually the same product re-badged by Turbonetics anyways. And although I have had my GT4088R repaired, again at a fairly high premium it seems I must send it back yet again as the repair isn't in my mind acceptable since the fin tips are not consistent in length. So although it is rebalanced properly I'm sure I have concerns about the surface area of each face on the turbine not consistently being driven by the exhaust at the same rate. I'm gonna post a thread with the repair and see what you guys think anyways. And ya, it was repaired at a fully authorized Garrett dealer and repair center in my city.
But the turbo itself is one of the most fun unit's I have yet had strapped into my car. Very responsive.