Okay lets see, well the .63 T3 Precision housing AMS proved flows the same as the Garrett T3 .82a/r exh. housing. Precisions .58a/r T4 housing out flows there T3 .63 housing according to Precision. To go bigger than the .58 w/o running insane amounts of boost and or nitrous might not be benificial. Although I do have a .68 in the closet just incase
First of all, what are your power goals anyway? Is this a track car or a street car and will you be driving it on the regular. The HTA86 makes almost spot on same power as the HTA88 and spools up like a standard 35r. People are upgrading from the HTA88 to this turbo.
9sec9 on evolutionm made 727awhp on the HTA86 at 42psi with standard 35r spool. Dyno Flash Al just made 632awhp and 592 torque at 34psi with this turbo on his STI.
http://forums.evolutionm.net/showthread.php?t=377950
I disagree but everyone is entitled to their own opinion, also the T3 housing can be mounted to the manifold directly w/o the plate.