2002 BMW M5 Structurebody Problems

THERE ARE NO POWER MODIFICATIONS TO MY VEHICLE, I JUST RECENTLY INSTALLED A LOWER MILEAGE ENGINE, ALONG WITH ALL OF THE PARTS SURROUNDING THE ENGINE AND TRANSMISSION (IE CLUTCH, FLYWHEEL, THROWOUT BEARING, CLUTCH FORK, ETC). THE BREAK-IN PERIOD FOR A NEW CLUTCH IS 500 MILES OF NORMAL DRIVING AND 1000 MILES FOR THE ENGINE. I COMPLETED THE BREAK-IN PERIOD ON SATURDAY JULY 20, 2019, FOR THE CLUTCH BUT STILL HAVE SOME MILES TO GO FOR THE ENGINE BREAK-IN, SO ON 7-24-19 I WAS ENTERING THE FWY FROM A STOP LIGHT AND WHEN I PUSHED THE GAS PEADAL IT SOUNDED LIKE SOMETHING EXPLODED AND I HADN'T EVEN GOTTEN OUT OF 1ST GEAR YET!!! SO, I PULLED OVER TO THE SIDE OF THE ROAD, B/C I HEARD SOMETHING RUBBING, AND CALLED A TOW TRUCK TO TOW IT BACK TO THE SHOP THAT HAD JUST INSTALLED THE NEW ENGINE. THE SHOP CONTACTED ME...