problem with rattling at 5000rpm to 6000rpm
 

hi guys been search and reading around the forums for similar problems encountered but still havnt been able to find any solutions to the cause of the problem or how to fix it....my 8 is turbocharged since may this year, running at 9psi dropping back to about 6-7psi around 6-7k rpm. about 2 months ago (after my oil change with 10w-30 semi synthetic) not sure exactly when but started hearing this rattling noise when at WOT as the rev's go up to 5000 rpm to about 6000 rpm...not sure if the noise actually goes away after 6000rpm or the engine sound is just louder covering it to redline. the sound comes in first, second and third gear havnt tried the others. no power loss, and sound only is heard when in drive, when its stationary and u rev in neutral no rattle is heard. i have also changed to bhr ignition coils, with new plugs and walboro fuel pump. noise still exist at those rpms with the changes. My EMU is chip torques exedy running with MAP. i use 98 fuel with 200ml's 2stroke for a full tank of fuel. also cleaned the MAF sensor yesturday and problem still exist. this rattle originally did not occur when i first installed the turbo was about 2 months afterwards to present.

also before i was experiencing random stalls while driving. for example i would be sitting at a light and the car would just cut off, it will start up in the first fire, also a couple of times i would be driving and shifting into another gear so going in neutral for that small period and the engine would shut off. this cut off would happen randomly maybe like 2 times a month? i know that there is no vacuum leak. i have changed to the walboro fuel pump 4 days ago and have not experienced any of this yet....my car has nearly 90000km on it with the original fuel pump prior to changing it. would this cut out be caused by the pump cutting out on fuel?
still have stock cat as well with racing beat catback
any ideas??