Update:
have finalized to purchase the I/H/E upgrade..:
Simota tube + K&N Uni filter
Mufflerland Mandrel Bent 4-2-1 (1.75")
FreeFlow muff (1.75")

Additional Questions are: after installing the IHE
1. would a Change from stock to an Aftermarket Adjustable Cam Gear give an effect to the cars performance?? have heard, llkas daw hatak pag nsa Slick or Track road
2. DO I need to make a General Tune Up and Reset my ECU?

Thanks sa mga nag replies, dami ko ng insights..