[carguy138]

Heat shield rubbing top of the driveshaft in front of the rear diff? Also take a look at the mounts and make sure the subframe is fully seated on the bushings.

For perspective, I had a BMW PE exhaust and sold it. Found it too loud (even with stock DP). I'm also running the stock dual mass flywheel (manual) and 335is engine mounts. I also found the stock runflats to be way too harsh and ditched those early on for michelin PSS tires.

all mods to give context (car feels like a stock E90 M3 in terms of NVH).
-koni yellows
-dinan springs
-poly front control arm bushings
-UUC front sway bar
-e90 m3 rear swaybar
-e90 m3 front strut tower brace
-e93 m3 rear chassis brace
-turner delrin subframe bushings
-turner delrin rear differential mount bushings (DID ADD NOISE but similar to a stock subaru STI)
-wavetrac LSD
-335is engine mounts
-PSS tires in summer/ blizzaks in winter.
-stock exhaust and stock downpipe.
-335is/550i clutch with DMF
-dinan front camber plates

everything else is stock.