I installed SlipLo scrape guard under the front bumper/spoiler of my Lexus LC500, but I have a bit of concern about its usefulness, and actually worry about it causing even more issues. My front spoiler/bumper is quite low, of course (why else consider this product). Installing this or any similar product actually reduces the clearance by the depth of the guard...in this case by ¼" . So if previously your clearance was 5" it is now 4-¾", so perhaps increasing the chance of scrapping a curb or low spot in the road. It will also increase the upward force on the spoiler and cause it to crack if you strike something with enough force. Granted this can happen without the SlipLo, but again, there is now ¼" less clearance, so a slightly higher chance of impact. Since these are attached with adhesive tape, there is a chance it will tear off on an impact thus nullifying any protection. Also, if you have PPF that wraps under the bumper/spoiler, the instructions say to cut it out so the SlipLo attaches directly to the bumper, not on the PPF. This can be a little tricky to do cleanly and without inadvertently peeling off too much of the PPF (and pulling some of it off on top of the bumper). If you subsequently decide to remove the SlipLo, or it gets torn off, now you don't have the PPF protection on that area of your bumper. The PPF provides some protection from minor scrapes on its own.
Bottom line: Despite these concerns, I installed the SlipLo. I attached it over the PPF as I do not have full confidence in the protection value of the SlipLo. If it gets pulled off, I still want the PPF there. It seemed to adhere very solidly to the PPF so I have no worry about it coming unglued on its own. Hopefully I can avoid any serious scraping on the front bumper - so I won't need to test if the SlipLo helps. Here's hoping it helps, and doesn't hurt to have it on.