update to the latest firmware. If I'm not mistaken, its built in to the newer firmware's. If you still have a rattle try and play with the lagfix. If that doesnt work you will need it to be adjusted physically....Go get some new turbos with the turbo warranty if its that bad
Make sure if you take it to the dealer take teh JB4 out before you take it in if the firmware update or lagfix didnt fix it.
Oh and when you upload new firmware make sure you go to file, then restore defaults to have proper settings
Hope that helps.
A/W E92 335i M-sport with JB4 G5 ISO/ E40 WEDGE PERFORMANCE BACKEND FLASH, Alpina TCU flash for AT/Switch-tronic +AR Downpipes, Stett gen 1 intake, Wagner-Tuning FMIC+RB Turbo setup/ RB PCV Valve+ Akro exhaust+60% E85/93 mix,+ HRE P40S wheels, KW coilovers, M3 sways,+BMW performance CF Mirrors, BMW Performance CF deck lid spoiler,+ CF interior trim, p3 vent boost gauge,+ LUX angel eyes (11.73@119mph on street tires) NO METH!