The 4 pipes are induction resonators. They can also be known as Helmholtz resonators. The primary task of induction resonators, is to reduce induction noise. In a NA engine, they can be turned to aid the induction cycle and boost torque. However on a turbo engine they don't reduce noise much and make no difference to the torque at all. Nearly all cars after the mid 80s had some kind of resonator in the induction system. More moderd engines are moving away from them. Mostly due to the little effect they have and the added cost of incorporating them.