Rick Titsworth said:  I’m building an un-pressurized ES with a TSIO-550E. I would like to put 8.5:1 pistons in it and run with 30-32”’ish MP.  Goal: Similar (350’ish) HP with cooler CHT’s and perhaps slightly better economy. I’d like to still maintain capability to deliver 32” to 25,000 ft.  Any suggestion on turbo sizing?

 Rick, I think the 8.5:1 C/R is a good idea.  I built mine at 8.5 to 1 and 38" max boost.  I think you will want the oversized Piper Mirage turbos if you want 32" at 25,000 ft. instead of a smaller turbo.  I built special intercoolers including billet end caps.  The billet end caps can utilize the sonic ports or they can be completely omitted.  The Legacy does not use the sonic ports as well.  Performance Engines may offer these new intercoolers and end caps.  Check with them.