With the car still on the dyno, I took the opportunity to perform a couple of quick and simple modifications to the stock intake system. The first was to remove the OEM charcoal filter residing in the top portion of the factory airbox. This brought about an average peak gain of 2.5 wheel-hp and 1 lb-ft of torque (this data has not been plotted). The second was to replace the OEM paper air filter for a stock-sized K&N equivalent. This resulted in an average peak gain of 2.5 wheel-hp and 1 lb-ft of torque. Net gains from these intake modifications are 5 wheel-hp and 2 lb-ft. This data is plotted in red on the dyno chart, showing peak output at 295 wheel-hp and 238 lb-ft.
Given the dearth of M Coupe aftermarket upgrades, these are good figures. Peak power has increased by 29 wheel-hp and 13 lb-ft. More significant are the effective peak gains, 42 hp and 23 lb-ft at the wheels, which also take into account the lightweight wheel/tire upgrade. The results may be even better when the vehicle is run on the street or track with full cooling and airflow.
Certainly, the greater power is most welcome and lively on the street. I also like the deeper, racier sounds (which aren't too loud or droning) and the Supersprint exhaust's great looks. At the track, things get even more interesting. Lap times have been reduced by more than a second, from an average time of 91.1 seconds and a fastest lap of 90.8 at the previous track outing, to 89.9 and 89.55 seconds respectively. Stronger acceleration out of corners and higher maximum speed attained on the straights can be credited for these improved times. This can be seen on the Traqmate GPS data shown. More seat time with the extra power should make it possible to reach a higher speed on the front straight (before braking heavily for turn one), saving a few more tenths. In the next installment, I'll be experimenting with a set of Nitto NT01 R-compound tires.