tqtran: Logically I agree that you probably can't bore out the Lokasil 986. These engines have exotic aluminum/silicone blended cylinder sleeves that are optimized to improve wear in a relatively thin area of piston wall. You bore through the sleeve area and you are left with aluminum that will wear out in a few thousand miles. You may be able to hone a few thousands and be left with a good surface, but the .25 inches or more needed to significantly improve displacement probably moves your piston wall out of the exotic alloy territory and into the high wear zone.
I don't KNOW you can't bore a Boxster engine, but it doesn't seem like you would get very much engine life if you did bore it.
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Take a look at the Boxster Preform on page 4 to see what I mean about the Lokosil Sleeve
http://www.kolbenschmidt.de/pdfdoc/dg_e.pdf
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