New engines today are so delicate. Need extra care for this and that. Sometimes when people used to bash Vios for the same 1NZ-FE that they are using, I don't think that is a bad decision... If they are proven to be reliable and simple, just use it. Change new engine, later new problem arises, everyone loses their mind. Like the Audi A4 thread where you mention it consumes engine oil like crazy. New high tech engine but still a lot of failure.But the intake plenum is plastic so should not easily transfers heat.
Yah, the plugs I think cannot use normal cheap plugs but I haven't change mine yet, still only 50k km mileage.
Yeah typical of ZTH what!