I installed a Jardine exhaust and rode it for 10 minutes between 3k and 3500 rpms to let the ECM tune itself to the new exhaust. It stopped back popping when I rev it up in neutral but it still pops quite a bit when downshifting or letting off the accelerator going down the road. Is a remap possible on the 2009 XB9's? How much would it cost to just have a dealer remap it to the new set up?