hahahaha..
if i don't change da extractor, i think da performance will still b good rite..
Then don't waste ur money.... seriously, ask any modder and the basic modification is I/H/E - intake, header (extractor), exhaust. With these mods you basically release the potential of the engine and probably get good economy gain. After that u need to crack the head (buka engine) and these mods are less cost effective (mahal)
With just the intake, u do not realise the full potential, can take in more air but bottleneck during exhale stage (exhaust). Changing muffler without larger pipings oso does nothing, just change the tone of the exhaust.
Don't waste ur money on other mods if you have not done the basic. BTW installing VS, grounding, plug & cables, FPR, LED, GT wing, muffler does not increase HP.
If you want to modify your car, u should start with I/H/E