I've ran everyone listed here but the Ultimate, Hands down Hughes Performance offers the best product out of the box the first go around. Bte a close second. I've ran so many converters I've lost count in the last 5 years. Sense I've started selling parts, I sell more Hughes and BTE product then anything else, because they can be bolted in and race for years to come. Not only that but they build some of the most consistent,fastest pieces you will see.
Nothing worse then a converter company missing by a mile and needing to yank it all back and ship it back.