Some owners will wonder why I kept the original air box in place?
Why not remove it all together?
The truth is, the filter (Apiro Torque) fits perfectly into it and almost looks ready made to sit the rear lip of it around the ring where the air box lid would be. Then there is heat soak which can easily rob you of any extra horses, the plastic OE box happens to be good at preventing that... Then there is also the dreaded deep puddle potential of hydro-locking your engine...
Again, the OE air box does a reasonable job of preventing this too, it has two drain holes in the bottom to release any splashed in water... The Apiro sits about 5" higher up and clear from the bottom of the air box so less chance of sucking up water than you would with a standard filter.
One modification I did do to the OE air box was to remove the V6 cold air feed to it that sits in the inner wing behind the splash guard. A 76mm 90 degree alloy tube now sits in its place with two stainless steel jubilee clips holding it into position, one on the inside of the box and one on the outside. So now I have the same diameter cold air feed as the induction pipe and throttle body with no natural bottle necks in it at all and it also sits up higher than the standard OE V6 or GTA pipe thus reducing water ingression even further. Just nice lovely cold air entering the air box
The induction noise is of a deeper note but not as tinny or intrusive as it would be without the air box present. Throttle response improved a lot on all three engine variants I have used them on.
Performance gains are subjective though... It seems a little quicker bearing in mind that the maximum you will gain is maybe 3-4 extra horses...
But the proof of the pudding to me was a steep hill that I travel up near my home... Previous to fitting the filter mods the engine would drop revs in top gear and inevitably I would have to drop down a gear to maintain the revs going up this hill.
After the mods:
The same car's cruised up the hill without having to change down and in fact the revs would start to rise
I also noticed a few added benefits too, all engines sounded much better with them fitted and complimented their distinctive engine notes.
Mpg... At first i didn't notice any gains probably down to the new addictive engine note which I wanted to hear all the time
But... after settling down and cruising along, it as quiet as the OE set up and on motorway journeys I noticed around 20-30 miles improvement per full tank (paying for all the filter and mods within the first two tank fulls)
It literally gives a new definition to "hitting the load pedal" and quiet when you want it to be From monster to a sheep in 1" of travel on the throttle pedal!
Was it worth it?
You damn right it was