custom pistons are quite pricey. Seeing as I just bought a pair of T3's..... As far as the .50 a/r goes that just tells me he needed a different housing, I guess I should take a look at mine. Well mine is .48a/r turbine housing and .42a/r compressor housing. However that makes no sense, garrett doesn't make a turbo with those specs. Either it isn't the original housing or the seller is wrong about the specs. I'll have to check it when I get home.