Removing Resonator Boxes From The Intake Pipe.


There has been mixed feeling about doing this.  Mitsubishi would not spend lots of money in the development and then the manufacturing of these things if they do nothing.  I have spoken to a few who have removed these and in most cases have heard the same thing.  Better top end.  While removing these increases the induction noise a bit it is not all that great.


The removal of these is so simple.  All you will need is 2 PVC end caps which you can buy from most hard ware stores for about 2 bucks each.  These will need to be the 30mm ones with an external diameter of about 40mm

  1. Remove the breather pipe from the induction pipe.

  2. Using a Phillips screw driver or a 10mm socket remove the clamp from the throttle body.

  3. Unclip your air filter top, unplug the ariflow meter.

  4. Now split the induction pipe and remove it from the airflow meter.  ( I have done this the longer way round as some of the clamps are a bit hard to get to otherwise.

  5. Remove the resonator boxes and push the end caps into the holes.  You will see there is a lip on the inside of the hole and this will serve to stop the caps pushing in too far.

  6. Use some silicone to smooth out the inside of the intake pipe and let it set as long as possible.

Reassemble everything once silicone has set and the job is done.  Keep the old resonator boxes incase you decide to put them back on some time.


Since having done this little job I have been doing quite a lot of research to find out why these resonator boxes are installed if they only quiet the engine down. 

The main reason is Volumetric efficiency.  In other words how efficiently the motor can suck it's fill capacity of air.  Some tests I have read about have, on the dyno, shown a definite slight drop in horsepower after fitting a straight through induction pipe and no resonator boxes.  One article quotes form on of the designers at Toyota that cars with airflow meters of any kind are designed to have a particular volume of piping between the sensor and the throttle body.  These boxes are specially made to help keep to this volume right down to the size of the opening of the box.  All of the articles do state that in a forced induction motor there is absolutely no reason to keep these boxes.  Click HERE to link to the tech sheets regarding Induction Resonators.  This link is thanks to Peter Scott from

Having said all of this on my Verada I have noticed a small drop in overall pick up off the mark but at the same time I have noticed a huge difference in the torque range.  On a steep hill at say 80kmh I would usually go out if overdrive and use 1/3 to 1/2 throttle.  Now the same road I am in overdrive using less than 1/3 pedal.  Fuel efficincy has increased as well.  The drop in pick-up I can live with for better fuel economy and low down torque.  I have kept these boxes and will give it a go on a dyno soon both with and with out them.  As for the OEM pipe, I have decided to keep it for now due to the fact it has been designed for this car.  I have no intention at this stage of converting to a pod filter until I can come up with a proper cold air box for one.

Madmagna : Thursday, 21. August 2003 15:47:42