Owning a 2006 LagunaGT 205 (RS225 engine), tuned to about 250BHP (measured). Really pleased with the result. Hardware mods are decat downpipe, 200cell sports cat, Meg2 RS250 injectors and rail, Pipercross panel filter. Looking forward to read/help with any possible tune or failure topic.
Nice project! Not being a hardcore Renault expert, I did not even know that they made a Laguna with the 225 engine!
They also make scenics, espaces and Avantimes, with a detuned version of the f4rt engine, they have a smaller turbo, not sure what other mechanical differences there are.