The runners may be tuned for resonance but it may just be that the engine has a high rod/stroke ratio. A high rod/stroke ratio likes longer ports to keep velocity up since the piston is moving slower. A nissian vq30 (60*v6) has very long runners as apposed to a vq35. Thier r/* ratios are 2.0 and 1.77 respectively. Same could be said for the S1 and S2.
So I did a little searching and the r/* ratio is not relatively high (1.72) and it has a variable lengh intake manifold. If I read right it is multi-variable using a valve to change length. It has "90 percent of peak torque is available from 1800 to 5800 rpm" which would explain the longest visible portion of the runner.
A variable length intake is not to be confused with a resonance tuned intake.
The old 1989 Toyota Corolla GT-* (with famed 4A-GE engine, as seen in other RWD GT-* Corollas and the first-generation MR2) had a variable induction system. At high RPM, I believe a set of butterly valves in the manifold opened or closed up. Boom, variable length.