Just to add. I went to see Fred at BTM Performance between Christmas and New Year and he confirmed my dephaser is shagged... He also pointed out that the aux belt tensioner looks like it's never been changed (previous owner had the cam belt changed for £150... say no more!).
Unfortunately Fred is booked out until February so I've taken the car to Speicalised Renault Services in Nuneaton, good bunch of guys. Should have it back by tonight! Hopefully I'll notice a difference, otherwise I may as well just get a diesel!! lol