Some months ago i fitted a Tomei Expreme Titanium decat 80mm exhaust on my Impreza Spec C Type RA. This beauty weight only 5.6kg and the sounds is a bit loud but awesome. With this exhaust i gained about 10ps than old Miltek 76mm. If you use the "tags" you can search on my blog and see the pics of this TI exhaust.
Here is a short movie of the car in 2nd, 3rd (full) and a the begining of 4th gear.