All the ones from china fit crappy, You just have to play with them to get the closest, best fit. Some of those gaps will disappear once you screw them in. Luckily, all the screws go in from the bottom. Use big stainless steel fender washers on the screws, that will help tighten it up a bit. You can get them at Lowes in the specialty drawers in the hardware section.
When I put mine on, I didn't use any double sided tape on the upper edge because it could be seen with them on and made the gap a little worse. The bottom screws with fender washers were enough to hold them tight.
Dinan CAI &Throttle body, ESS Tuning TS2, Bimmerbrakes gen3 headers, UUC SSK & DSSR. Achilles oil pump, VAC oil pan baffle
M3 Motor mounts, UUC Trans mounts, Modified clutch style LSD 3.15, TMS front subframe reinforcement, Koni Yellow sports,
H&R sport springs, UUC sway bars, BMW Perf. Rotors, UUC SS brake lines, Hawk HPS pads, CSL replica wheels,
Rotora strut bar, FXR HID conversion, M3 Mirror conversion, BSW stage 1 speakers