Exhaust & Air Filters
Regarding exhaust and air filter combos, you are by no means limited on the Metro Turbo.
For exhausts, there are no real big power gains from aftermarket exhausts, there WILL be a gain,
but don't expect a great deal, the Metro's system is already quite adaquete!
For a full system, ie downpipe back, you should consider Janspeed: ( www.janspeed.com )
Oh look, loverly `aint they?
They come in a mild steel, so its not expensive, and they have a nominal sized rear pipe, ie about 2" stainless outlet,
so at least you won't atract the fuzz!
They are relativly easy to fit as well, so it's not too much a bother.
Expect to pay about £140 for a full Janspeed system for your Metro Turbo.
Or, you can consider Peco: ( www.peco.co.uk )
Which the Metro Turbo version is a SINGLE 3" pipe, but it is the BB2 version.
The Peco range are more for looks and sounds than performance, they are slightly cheaper than Janspeed,
about £110-£120, and they feature a nice 3" chrome outlet, and they purr and growl!
Ok, so if there is little power gains from a full system, and the `nominal` size of 2" outlet does not take your fancy,
they why not go even cheaper, and buy just a rear silence/back box?
You can get these from £50-£80, and can be got anywhere, from Les Smiths, to Woolworths (probably)...
The most popular being the Peco range, they're about £70, sound and look the part!
I have a Peco BB2 single back box, and it really sounds the business!
Ok, on to Metro Turbo filtration...
The Metro Turbo has what I call a `remote` filter box, ie, the air filter is housed near the front of
the engine bay, with a pipe fed to the turbocharger.
Now, there is 2 options for upgrading the air filter, either by a performance element, or a cone filter.
The performance element, is nothing more than a straight swap for the crappy paper element in the box.
It flows more air, filters more air, and has small power gains.
The best element to go for without doubt is the K&N range, normally about £35 for the element:
With a million mile warranty, it can't be beaten!
Reasons for fitting an element over a cone filter?
Easier fitment, no mods required, relativly cheap.
Ok, so what about cone filters?
Well, K&N do a universal range, just junk the old airbox, and measure the size of the pipe to the turbo.
Then find a cone filter large/small enough to `plug` onto the pipe.
You will then have to mount it securly somewhere, and also find a way to ensure the oil breather goes back
to the turbo where it was originally.
The best way to ensure good fitment, is to strip the old airbox, leaving the metal case, ie, cut all the
plastic away, and leave the metal mount on, then you can place the cone filter on it, and the breather
pipe will still be connected.
Other makes of universal cone filter, are Ramair, and PiperCross:
Pipercross filters are of a foam type
Whilst researching the best type of filters, I have read a few articles regarding the cone filters with turbos.
Because of the increase air flow, the turbo fins, which drive the air through the turbo itself, have been
known to be damaged due to cone filters, whether this is something to consider, I don't really know!
Also, because the cone filter draws air in from all sides, the engine side is hot, so it will draw in small
amounts of hot air, which you don't want, because cooler air = more power!
Whats the advantages of cone over element?
Cone gains more power than element filters.
They sound `louder`.
And they look better under the bonnet.
So, in conclusion to this, I opted for a K&N element, and drilled 0.5cm holes in the front of the airbox,
thusly increasing airflow, and sounding better.
But the choice is yours.....