If I may, I would like to publicly address these concerns. I will start with the Rear Diffuser.
The fitment issues seen in the posted photos do show a gap slightly larger than what is expected after install. On our test vehicle, we did not have as large of a gap as what is shown above.
However, it is a fixable issue. There is an additional step that may be necessary on some vehicles during install (adding a slight bend to the metal brackets behind the OEM valance). Not all cars are identical when you get into fine measurements. The rear diffuser was built off of our test car and had very good fitment and did not flop. (I will attach the photos of the one on our test vehicle and am more than willing to take any further pics if requested).
I do admit, this possible extra step should have been included in the install guide. But we had no evidence that it would be necessary until we were contacted about the issue. As soon as I was made aware of the issue (yesterday evening), we began working on a solution, and updated install instructions were emailed this morning to everyone who placed an order.
This is a new product, sometimes unforeseen things come up. But we stand behind our work and always strive to provide excellent customer service. That is why a return for a full refund was offered to the OP prior to this post (which was refused, but is still on the table).
As for the Spoiler extension, this is the first complaint we have received on the quality of the part. If we had been contacted about it by the OP before it was installed, a return for a full refund would have been offered.