Hi. I have a Nissan Sunny with a QG15DE engine and i was wondering if there are any small simple upgrades that i can do to this engine and car to improve its performance. not looking for a monster but rather a "better roar for the meaow" that it has currently. i did install Bosch Iridium IXs - BRR5E-11 and running Castrol GTX 20W-50 but thats about it. i did get a better "purr" from it though and a bit more talk from it on running. the fuel quality here i use it 95 Octane so with all this information can anyone suggest any ideas on how i can further better the "purr and talk" thanks all in advance