Is my L shaped implant extruding? If so, how soon do I need to get a revision? What is the downside of using rib grafts? (Photo)

Unfortunately silicone in the nose cannot stay permanently and will need to be removed at some point.  Since it is a foreign body it never becomes a part of your nose and instead continually thins the skin around it.  This can eventually cause a break in the skin, leaving an exposed implant.  
The issues you had with the redness in your tip and the extrusion of your implant may be reduced with the use of tissue from your own body (autologous grafts).  Autologous grafts have a much lower rate of infection and migration because they become incorporated into your nose and fully become a part of it, instead of remaining as a foreign body like Silicone and Gore-tex grafts do.  It is possible to achieve significant refinement and augmentation with autologous grafts just like synthetic grafts.  
An Asian rhinoplasty specialist, experienced in revision cases, will best know how to remove the implant and reconstruct your nose.  Your nose can be reconstructed with tissue from your own body, giving you a permanent result.  

Hello,The sooner you get a revision the better. The implant is causing irrevocable damage to your nasal tissues. Rib graft is your only good alternative to achieve the same result your L implant gives you: dorsal augmentation AND tip projection and nasal length.  Ear and septal cartilage are too weak and too short. Proper shaping of the rib will significantly reduce the risk of warping. Go visit a few ABPS certified/ASAPS member surgeons that specialize in rhinoplasty. Best of luck!

it appears that you may have a possible thinning over the implant. See a very experienced  revision rhinoplasty surgeon if your surgeon is not available. The implant can be removed and replaced with septal or ear  cartilage without needing a rib graft. 

If you're visualizing a bump and thinning of your skin at your infratip lobule, you could be starting to extrude your implant. Silicone implants work well in thicker skin types for elevation of the nasal bridge, but the L-shaped implants that extend down your columella are the ones that may extrude - typically by the tip. An examination by a revision rhinoplasty specialist may be helpful to see what might be best for you moving forward. Wishing you well. Dr Joseph

Synthetic implants can extrude at any time, even if you've had no problems for many years. Early signs are mobility, redness, swelling, and thinning skin. It's best to be treat it before it breaks through the skin. The implant needs to be removed. It can be replaced with your own cartilage. If the implants is large, you may need a rib graft. The downside with rib grafts is the risk of warping. Your surgeon needs to be familiar with carving cartilage for a safe and happy result. Safety comes first.