acoustic removal is easy. its in the passenger side wheel arch, its got a butterfly mechanism in there and its smaller bore that restricts airflow. took me half hour to 45mins to remove. really easy tho, search 'acoustic valve' and you should find an easy step by step guide to removing it!
and yes, a decat pipe will go straight onto your standard exhaust. it should again take around half an hour. its 3 bolts, and unscrewing the lambada sensor. you will need a manifold fixing kit tho, only £16 from renault. only thing is tho, you will need to remove it at mot time.