Depending on the torque band that u prefer, u can mess around a bit with the exhaust setups. Get the swirling bullet with hotbits extractor, u'll never regret it & ur low end torque band changes tremendously.. LCP helps, air filter helps from 3k RPM onwards, or u can go straight for Cold Air Intake. Carbon air intake will help as well, but this requires the dismantling of ur original airbox and replacing it with a open-pod air filter, as well as building a heat shield around it. This works very well to improve low end torque, but high end ur car will suffer kaw kaw..
Once I used the wrong setup (wrong bullets & extractor) on my PE's exhaust system, I went to Duke, press till habis my top speed 160 only. Low end power cannot be felt at all. So it was practically useless, that setup. My car's idling became very bad during cold start due to improper placement of O2sensor, and it scared the shit out of me a couple of time when I step on the accelerator pedal & there's no response. This is because the O2Sensor works with the presence of heat & exhaust gas, and so the exhaust shop fella placed the sensor AFTER the flexipipe (a.K.a nenas), causing the O2sensor to not be able to get any readings during cold start & wet weather because the flexipipe sort of insulated/separated the heat from the extractor & the sensor.
What I did was I revamped the whole exhaust system, chunked away the cap ayam extractor, plonked in a Hotbits' extractor with the O2sensor at the intersection of the 2nd & 3rd pipe, a swirling bullet, and a midbox. Tested the power after that, damn impressed. Then I replaced the original muffler with an aftermarket S-flow, been happy with the power ever since till it's now passed into Zeng's car.
