Is an airbox & a throttle body the same thing then? (Genuine question, I'm clueless about oily bits)
What else is involved (other than the plenum that you mentioned) in the upgrade to X51 spec? Is an upgrade to X51 spec your goal here? Project: Ultimate C2S?
What changed between 997.1 & 997.2 C2S engines? Power went from 355 to 385 didn't it? Did 997.2 C2S include X51 as standard, or did something else change (map etc)?
Nope they are separate, just X51 air box hose only fits the larger throttle body, I'm using an Maxspeed plenum, not X51 plenum as am keeping the stock intake manifolds, as removing them is a lot of work and the gains is unknown.
Full X51 spec was dual intake box with dual filters, larger throttle body, X51 plenum, intake manifolds, stiffer spring in cylinder head for higher rpm limit, X51 exhaust manifolds, PSE exhaust, 600 cel cats and X51 remap.
I don't have X51 intake manifolds, x51 plenum or modded cylinder head. These I don't intend on bothering with, a nightmare to fit and the gains in the X51 kit are said to come mostly from the bits I've gone with. On top of this I am however using better flowing filters and have 200 cel cats which flow much better along with softronic map.
997.2 engine went to 380BHP as Porsche moved to direct fuel injection giving more power and much better economy. There was still a power pack option which took them to 404BHP area but was a lot cheaper as was not carbon.
Mine when done will hopefully be somewhere in 385-395 area hopefully, the biggest gain comes from the 200 cel cats as a individual component.