Thanks SilverBuick and MBHD. I've read about casting and forging parts but obviously can't tell the difference by looking at them. I observed some rough edges alog what looked like the seam line of a mold and assumed they were cast. I don't have a great picture of it but...
So.. I doubt Tom has ordered my new pistons yet so the target compression isn't final, but the machine shop was fairly convincing a lower compression like 8:1 would support good milage, 87 octane, quick spooling and a mid-high power curve. They said the turbo would need to boost a bit more to get the power but it would be less prone to detonation and work well for me. I'd like to think they were taking all my components (turbo size, external wastegate, water/alc injection, cam) into consideration but I don't want bad mileage or sluggish low end performance. I'm not a fan of conflicting information. I'll have to look into this more over the weekend.
