This article explains some of the conditions required for the burble to occur:


On the Cupra, this is more prominent in Sport and Cupra modes only.

In terms of the burble, there could be many reasons why it’s not so prominent, such as exhaust/cat temperature or the type of fuel - some people state that different fuel brands have a different impact or the differences between winter/summer fuel grades.

In addition to the driving modes above, quite a few people have asked if the mode changes after a set period of time eg 30 mins as the burble lessens after a longer drive, in a similar fashion that the exhaust note changes after a cold start.
 
I get it on both 95 and 99 ron, Do remember when turning the car on even though the profile selection says sport indiv or cupra its still on normal as the handbook says you must re-select it.