i guess breaking/building four six fours i kind of know what i am talking about? (these are personal ones, I don't do it for a living)
you could build it with the best parts in the world, you still have no control over a hpfp taking a crap and wiping out your fuel system, or hanging an injector causing a melted piston, destroyed block and bent rod. Lifters are a crap shoot too, by the time you realize one has gone bad, you've eaten the cam and sent shavings thru the whole motor...and with any luck, sent needle bearings thru the lpop. The lack of top end lubricity in these motors causes excessive wear on rocker arms and bridges that will need to be tended to frequently.
I could go on and on but you get the point. When these things fail, its never a simple fix-kind of like how you cracked a piston you know? Turns into a motor build. Ya, thats the life of running a six four.
I dont dispute they are a ton of fun and have the potential to make big power. For a toy-sure. For reliability-nevah
on edit: J&K lol the email address is a gmail account, and their site says that 08-10 E-series vans use six fours haha no way in he!l i'd use them...