Exhaust manifold design

[Rippthrough]

Typo, and no, it wouldn't need more boost, that's the point, it's already making enough torque to hit that without the limiters.
Two different sets of regulations, you can't directly compare them without trying to make it equivalent - even a years difference between the Audi units makes a massive diffference to bhp/litre as the regs change - what you can do is look at what they've done and why they've done it...and if you look at why the Mazda unit uses that manifold, it'll be damned well obvious, if you think that's an easy and basic design to make you'll get a shock...