Changing to a open pod will not exactly erode the engine. If you
use a K&N fiilter or of the same grade then it be ok, only
thing you need to lubricate your filter. Open pod suppose to bring
in air faster so that the engine could burn at a more effective
rate, but seriously it does not gives too much of any improvement
just that you have a louder intake sound.
Straight thru exhaust is usually for car with higher boost
however it is illegal since the catalyst converter would most
probably be removed.
But why would a taxi want to drive so fast? Need to chiong at
traffic light? take it easy lah, for the safety of your passenger
and yourself.
And lastly, Estima is surely bigger than a Wish......