New plugs 3k ago and all well so far (touch wood)
. I'd say that v400 asks more of the car, well it feels that way anyhow as I've honestly never driven anything so fast. It makes the less refined v301 feel a little slow.
I spoke to COBB about my above problem and they have been superb in helping me out. I've updated the AP again to the latest beta firmware and all is well. Top customer service!