Must be unlucky!
I have had the Jardine system on for 2 weeks now. Done turns on like a switch at 2,000. I had the same problem with several straight pipe, larger muffler attemps on my 96 5sp.
The system sounds great except for the drone which even covers up the turbo whistle (I have a amsoil AF).
Would love to loose the drone but keep the Jardine!
System was very easy to install and fit like a glove.
jjw