I have an 01 f4i. I bought the pimpbike.com undertail from them off ebay.

Pros:
- The undertail was packaged nicely and arrived promptly.
- It is made of fiberglass and of sufficient strength.
- Overall nice quality.
Cons:
- The lock hole was not sized correctly for the lock. I had to drill it out a bit and file a notch for the locating "tab" on the lock body.
- Once painted, the mounting was a bit cumbersome because of the lack of flexibility of the fiberglass. The 4 plastic rivet holes did not easily line up with the factory tail section. Once I did get them aligned enough to place the rivets, there was a fare bit of tension placed on the factory tail section. I had to apply upward pressure to the tail section to get the mounting holes lined up to the bike. Some paint was scratched off in the process.
- The "instructions" were sent via e-mail in .pdf form and were marginal at best. The "license plate bracket" mounting portion of the instructions was left intentionally blank as if to protect a "trade secret" and an email sent requesting the "instructions" went unanswered. The "bracket" is nothing more than two L shaped brackets from any hardware store. Nothing special or complicated about them.

Pimpbike.com offers "painting tips" which is nothing more than how "they paint" their parts by scuffing with 400 grit, priming and rattle canning it with color matched paint from Napa. Hardly any "tips".

Overall I'm happy with the product itself, but less than impressed with the rest of it.