That burn looks pretty decent for the H552B, which is known as a drive with quite horrible burn quality.
As for what speed to scan at, I suspect 4x is correct. The H552B uses a chipset from MediaTek, similar to Lite-On writers. I don't know much about Samsung/Toshiba writers though.
if i have a tsstcorp cd/dvdw ts-h552b ga04, would this be samsung or toshiba?