whistle sound help help help!!!!!! reward?

hi all, guess you have read my recent posts about a rasp in my exhaust system with janspeed back box, well today i bought a standard back box as i was sure there was an issue in the janspeed!!!! wrong!! its still there and i am at my witts end trying to solve the problem, all the standard box has done is slightly quite the rasp/whistle sound down a bit!!!! it sounds just like an after market turbo whistle but there isnt one!!! i have had the exhaust checked 3 times for leaks and there is nothing leaking no where, the car sound fine when stood its only under load, i really am totally foxed by this, if anyone recommend a solution i will personally send them £20.00 as a thankyou as i have ran out of ideas only thing left to change is the flexi pipe but its only 3 yr old and done about 6000mile and looks like new to be honest..please please help!!! i also have the z&f buble/pop andthat now sounds more like a puff puff!!! thanks all for your thoughts and help steve

from the last news http://ift.tt/1kM2USU

via IFTTT