nailheapowered.
What type of turbine housing downpipe setup do you plan on running?
What headers do you currently run?
What size CI motor are you running?
Are you going to run any Heads up Buick classes?
Reason I ask is, there are 8 different turbo configurations you could choose from in the 72,74 & 76mm size. Sure running a T4 Tangential style turbine housing will make more power, but if he's planning on running a Buick specific heads up class, there are rules that will limit the type of turbine housing used and the size of the turbo itself. I hear what you are saying WhiteT78Supra and do agree with you on some points, but these two applications are totally different. Mainly because the 2JZ is a million times more efficient than the LC2 with regards to head flow and rpm range. I've learned this not only from feedback from my Supra customers when I was at PTE, but also from my Buick friends who've run the exact same turbos that the Supras have run. The biggest would be the GT5531 and the GT4788 on all out Stage II headed TSO 1200hp+ class race cars.
If you are not planning on running a class that mandates a specific style turbine housing and the motor size is 248+ CI and you don't mind running whatever downpipe and wastegate you need to make it work, then I would suggest a PT74 GTS with dual bb and a Tangential .81 A/R housing. (1050 fwhp rating)
If you are running a class, then there should be a rule that states maximum turbo size allowed and turbine housing style.
If your motor is 231-235 CI and you want to maintain the 3-bolt style turbine housing, then you are currently limited to the GT-Q turbine wheel, until someone designs a larger 3-bolt turbine housing to work with the GT-S and the X trim turbine wheels. PTEs current line of 3-bolt Buick turbine housing turbos are made for the GT-Q turbine wheel. They offer both a .63 A/R and a .85 A/R turbine housing. THB3-80 and THB5-80. (Turbos include, 70 GT-Q, 71 GT-Q, 72 GT-Q, 74 GT-Q and 76 GT-Q in journal bearing or dual ball bearing.)
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This might be changing in the near future, but nothing official has been said yet.
Hope some of this helps.
Patrick