ProMaxx and IMM aluminum small block LA heads

I bought a set of the Promaxx castings (63cc, 171cc/77cc) from Todd at Marsh Performance back in 2017. Todd had them ported by Larry Smith and then Todd reassembled them and sold them to me as the Sidewinder heads. I have had no problems since the day that I received them. But Todd assembled them and checked them before he shipped them to me.

Since IMM (Brian) is a member, I would suggest discussing your options with Brian. If I was to purchase another set of heads, I would feel much better about buying them through another vendor (a shop) rather than just buying them from an online store. (Unless you are an experienced person who knows your way around these heads.)