Big Bore Exaust backbox which one for citi

Hi all,
        i am after fitting a big bore back box so it gives the car a nice beefier noise not too much thou.
Question is as mine is a 1.3 with the 1.6 block, which back box can anyone here recommend please which needs no modifications to fit plus will sit and look right on the car without sticking out too much and not over the top, plus what size would look right.
Best wishes and thanks for help