I have owned a UK wr450f 07 since new, I have opened out the air box, and installed a Dep S7 full system exhaust. I have removed the AIS and grey wire. I have spoke to my dealer about re-jetting and he said I will be fine with the stock jets? He said when they are imported over here they are re-jetted to suit. Is this correct or am I doing my bike harm? it runs fine and has released alot more power.