Once again left the door open for some additional engine performance improvements with the new GT4 by continuing to utilize the same factory intake found on the 981 S and GTS models. These intake systems employ the smaller more restrictive 74mm throttle body which limits power and torque potential. The new GT4 may have the 991 Carrera S 3.8L engine but it did not come with the larger 82mm TB that is OE for both Carrera engines. Again, P is famous for controlling engine output by choking the inlet tract with a less than optimum TB size. This has handicapped the Cayman from treading on Carrera territory and the now it shackles the GT4 from entering the ring with the GT3.
P claims the 991 Carrera S delivers 420 HP and the GT4 delivers 385 HP but if they are the same engine why does the GT4 produce a whopping 35 less HP? This means the GT4 engine is only 15 HP stronger than the 991 Carrera Non-S 3.4L engine. Of course these are only advertised figures and as we all know, “tuning” plays a crucial role in engine output. The bottom line is that Carrera S engine benefits from the IPD Plenum without a larger TB, so the GT4 should perform even better with the Plenum and more appropriately sized 82mm TB.
Comes with 74mm P Throttle Body. This is the larger, German throttle body required to fit the larger 74mm “Competition” Plenum.