There is info on the site, buyer beware mostly. Basically, if you get a good one, they work well. However, some don't have passages drilled, some are crooked, and of course they fund a country we are trying not to be reliant on.
Second, my experience is that there really isn't any magical gain of an RPM over a SM, especially if you do the Edelbrock mods to the SM. However, unless you can port yourself, likely cost more than the Chi-intake.