35WHP seems like a huge gain. Also, if their baseline was 305 WHP, their STI is already significantly modified. Depending on they dyno, I'd guess at least they at least have TBE, custom reflash, bigger injectors, and 20G or FP green sized turbo.
I'd also like to know if anyone has any independent experience with this intake manifold.
I have only talked to about 2-3 people on NASIOC that have had their car tuned with that intake manifold. FWIW, I have been told by them that it would only really benefit someone who didn't mind to sacrifice some low end WTQ to get an increase in WHP. Also, in their oppinion if you are not running upgraded heads, less restrictive exhaust, and a high RPM motor, then you won't benefit much from it. Not to take any engineering credit away from Magnus. They do know how to get numbers out of cars. IMO, if you are not planning on running a rev happy motor then you won't get tap into what the intake manifold was designed to do. Don't forget that your tuner makes all the difference.