I have a 76mm turbo on my otherwise stock 6.1 hemi. Idles great, drivability is good, it runs absolutely perfect at or below 9 psi of boost. When I start turning the boost up above 10 psi I am getting a weird shudder at WOT that is audible and you can feel the loss of power. Raising the boost from 9 to 12 is actually lowering my 1/4 mile .4 seconds. Plugs are gapped at 0.028, running on E85. Logs show no knock at either boost level.
My tuner is out of ideas so I am reaching out here to see if others may have experienced this.
No_shudder_log.hplShudder_log1.hpl