The Metro Turbo comes equipped as standard with a Garrett T3 Turbo. This is quite a large unit and is not ideally suited to the small displacement of the 1275cc A-Series, despite the small 0.25 A.R exhaust housing. {though on large displacement or high power motors there may be an advantage in going to the bigger 0.36 Escort RS Turbo exhaust housing}
Due to the size of the Turbo unit no real boost is seen below about 3-3,500 rpm. This may be fine for a race car running at full chat most of the time, but on a road car it is not ideal. There is a certain amount of "lag" before the Turbo finally comes "on boost".
Changing to a smaller Turbo will bring the boost in much lower in the rev range producing a much livelier and responsive engine, with a Torque curve better suited to a fast road application.
One Turbo which seems ideally suited to the 1275 A-Series is the T2 unit from the Renault 5 Turbo. The later units have the advantage of including a water cooled housing.

So you fancy a T2 on your motor ?
There are three options then:
{1} Modify the Metro Turbo manifold to accept the T2
{2} Make a custom manifold
{3} Use the Mirage kit

It is possible to modify the standard Metro Turbo manifold to fit a T2 Turbo, though this requires a bit of work.
To convert the Metro item:

• The existing studs will need to be removed and new ones drilled and tapped.
• A spacer plate will need to be made to go between the manifold and the Turbo 
• The compressor housing will need to be rotated
• The actuator will need remounting
• An oil drain will need to be made
• A custom downpipe will need to be made, or you can modify the Maniflow item to suit, as i did.

This is a picture of the Metro manifold i converted for use with a T2.
You can see the spacer plate fitted to taper down from the manifold to the smaller exhaust housing.

Fitting a T2 to the Metro manifold will still require a bulkhead box to be installed in the shell to provide clearance for the Turbo.

You could also make your own manifolds up {pictured here} as my friend did.  Though this also required the bulkhead box to be fitted.

If you do not wish to cut the bulkhead of you shell, there is one way around the problem. Mirage Motorsport sell a stainless manifold set which will allow the fitment of a T2 and some T25 series Turbos without a bulkhead box needing to be installed. You'll still need to do the other jobs as when you fit the T2/Metro manifold though {see above}

This is the Mirage Motorsport T2 manifold. With Renault Turbo fitted.

If you don't fancy making up your own manifolds for a T2, or adapting the standard Metro item, then why not visit mirage motorsport. They can provide you with a manifold kit which includes an exhaust downpipe, Turbo elbow and an exhaust manifold. Made from high grade stainless and backed with a lifetime gaurantee !!