I'm going to build up a new bottom end as mine currently has I need to fit mine with steel rods and has a little piston slap, it's irritating me sounding like a deisel. But what pistons shall I use?

My current bottom end has Accrilite Forged pistons, but I found a set of early Mahle Forged C20XE pistons (very very cheap) so bought them. Which would be better? I know the XE pistons will give me comp ratio of 7.8:1 with a CVH head and Focus RS headgasket IIRC but not sure what the Accrilites have been machined to?

Also the Accrilites have been machined with flat crowns and I have been told that at higher boost they will possibly damage?