It's all of those US parts that make it go faster - about 75% of what's inside this engine is made in the USA. APE upper and lower studs, Carollio rods, Wiseco Pistons,pins, and rings, Megacycles camshaft, Kibble White springs, titanium retainers, and stainless valves, Barnett Springs, US made oil cooler, K&N oil and air filters, Jegs stainless cooler lines, Keker exhaust, Dyna 2000 electronics. Heck, this may just have more US parts than the 2006 Harley Davidson which was 49% imported.
Glad I could be of help.
Gordon