If you are going to build a 1600CC (or 1835cc engine and run it at 3600 RPM or less), I think most folks would recommend sngle port heads (because the intake velocity will be better and you'll get better cylinder "packing" of the charge for better torque at a given RPM). There are fewer choices in single-port heads. Maybe that makes selecting the best an easier one. For bigger engines: Sonex/Aerovee in the past used Mofoco heads, and reports have been mixed. I think some were recalled. I have a cracked one on my plane right now (cracked between the valve seats). Now, Sonex is reportedly sourcing their heads from EMPI, and at least one guy who bought them had to get a valve job done on a brand new head to get the valves to seat correctly. Revmaster has heds made to their spec in China. They are very good quality and have reportedly been engineered to cool well. A few quirks (e.g. to get to the lower plugs you need take off a panel, which introduces another spot for leaks) and not the cheapest heads, but they have a good reputation. I don't remember what GPAS and Scott Casler are using. These are the dual-port Panchito heads from CB Performance? How have they worked out for you? I can't recall what size engine you're running. I've heard the air passages are better than most, and they claim to have one more fin. Valves are 40mm intake, 35.5mm exhaust, which is the same (too big) size as is common in the street performance heads. But, I understand they've changed the valve geometry a bit and moved the valve guides so the valve seats are farther apart, which would be a very welcome change to help avoid cracks between the valves. So, if the valve stems come up to the rocker arms at a different angle than they do on my present heads, I guess I'd also need to make adjustments to the rocker arm locations and maybe cut new pushrods? And, for those of us running dual plugs, is there room for another hole in the Panchito?