I'm also a Diamond piston user. Very nice product. Also where the Speed Pro and KB pistons are made could be a factor. Some of the inexpensive cast versions are poorly made (overseas) with tolorances all over the place. It can be ugly. Do you really need a .060 piston? That's about all she can take with minimal coreshift. Probe sells a few 390-410 and 428 pistons dish and flat top for $500ish. I think they are forged but you'd have to check. Also have you tried to call Diamond direct? You can if you haven't. Some vendors might be able to get a better deal as well.