When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Your right I stand corrected, I did just look it up. However many have pushed pasted the 400 HP mark many times, long term, without issues. IMO it is all about proper tuning.
Blocked off (the one on the cylinder head flange), if a customer wants it drilled/npt tapped, they can let us know when they order, or we leave a nice flange for that customer to do it on their own. Either way there are options.