20psi on a t28 is past the efficiency area of the turbo. Have fun killing that heatpump quickly.scherger_16 wrote:doing full motor build wondering what head gasket to use have a 86.5 bore t28 turbo probly run 20psi boost i head not to use cometic what head gaskets are good what are not. also the thickness how much is this gonna affect the compression ratio should i go to 9.o to 1 with a 1.1 mm gasket so i dont loose the compression ratio on a 8.5