Sounds like a good reason to support companies like CP, Ross and RaceTech pistons, and Molnar, Scat and Eagle for cranks & rods.
From what I've seen, CP and RaceTech BBM pistons are a generation ahead of the stuff that Diamond and Wiseco offer. I like Mahle, too, but it's all 4032 alloy for BBM and the selection is pretty limited (e.g., no dish or dome options).
Maybe thats what you have seen.. myself.. I bought
a set of Diamonds the last time I bought.. they
were very nice.. I did have some custom specs to
them and I picked them up in 3 days.. the numbers
were right on and the finish was very nice.. they
didnt looked as good as my PCs or at least damn close
Never questioned Diamond's & Wiseco's machining quality. But their (and Ross') piston blanks for BBM look like the same ones they've used for 20+ years. CP's take those a step further in terms of weight, and Mahle & RaceTec use more current skirt designs & shorter pins to reduce weight compared to "traditional" designs.
When I ordered my CPs I wanted them light weight
so they cut extra out of them.. they were a very
nice piston but the extra work I had done on the
Diamonds they didnt look like and old stock pistons
and for the small added cost for the work and the
time frame I thought they were very nice.. if Bob
(Bob Fox) does sell the company I hope they keep the
quality up
EDIT
Also on a CP piston if you make any change its now a
custom piston unlike Diamond that will give you up to
a total of 3 changes before they call it custom.. and
it was (when I bought my last set) $35 per change to do
8 pistons so I call that cheap.. I changed the pin height
and added a FAIR amount of dish to run my W-2 on pump
swill 87
