Best source for 4.1L pistons/hypers are out??

[Powder]

Im just getting started on my 4.1 build and have been talked out of using hypers by my machinist and Summit Racing. So much for my budget build plan!! Now I don't know where to go to get the custom pistons (I assume) that I will need. Do you normally buy direct from the well known manufacturers or through a Buick vendor? Any recommendations will be very much appreciated.
MLH

 

[Turbo1dr]

T/A Performance

T/A Parts Catalog

 

[Powder]

Thanks for the info. I didn't see any 4.1L pistons referenced but that's to be expected. I'll give them a call.
MLH