Firstly, congrats on the Clio 3. I had mine for about 4 years and have lost track of it after it was sold to a dealer in Melbourne.
Would your's happen to be a black 2010 with rear wing?
Secondly, the exhaust is not needing any mods IMO. The suggestion to fold the rear seat if not in use gives ideal sound and if your front speakers are still the stock little ones, you should put in some nice JBLs if you can still find them, but if it is my old car, all four speakers have been replaced already.
I had no issues with the bluetooth but I only ever used it to receive calls, not make them.