TEGIWA 70MM Cat Back Exhaust System. This perfectly crafted cat-back exhaust is made from the highest grade 304 stainless steel. The pipework features 70mm pipework from the manifold back. 70mm is the perfect diameter to retain clearance, relatively low noise levels and good power increase. The tail box is a similar size to OEM in order to keep sound levels low enough for track days - it's within the limits for all UK tracks. If you daily drive your FN2 then this is the exhaust for you! The exhaust gives performance gains of around 4-8bhp over standard un-mapped, whilst also reducing the vehicles kerb weight by around 5kg.