Supplies:
Structural plastic repair(paint supply store)
plastic spreader
fiberglass cloth and resin



here is the gap of the Si lip on my 98






The first thing you need to do is make molds of the sides w/ fiberglass.

Make the mold here:



You will use these to hold the pieces together when your putting the plastic filler on. I don't have the molds here with me at school otherwise I'd take pics of them. Make the molds about 8-10 inches long on the side of each lip where you will be cutting. Use about three layers of fiberglass so they will be stiff. Next decide where you want to cut. I cut about 3 inches from the edge.

Cut around here:



The measured gap was 7/8 of an inch. The cut was made with a jig saw. Then put the lip and the portion of the lip that you cut off inside the fiberglass mold you make. Use something to hold the pieces to the mold. I don't know what the things are called that I used. They're black and are sold a grocery stores. Like clothes pins but much smaller and stronger. After the peices are inside the mold measure the gap to make sure its 7/8 of an inch. Cut some fiberglass cloth 7/8 of inch wide by whatever the height of the lip is. mix the plastic repair and spread it onto several pieces of the cloth. Begin filling the gap with serveral layers of cloth on the backside of the lip. The fiberglass mold is used as a backing when filling the gap. Once you get enough layers to fill the gap, finish the back off with a couple large pieces over the gap.

This pic sucks but you can kinda see where the gap is filled:



Heres what the backside looks like:


Allow that to dry, remove the mold and sand down the front side of the lip. Apply a layer of plastic repair to the front side and sand smooth with 80 grit on a block. Continue applying layers and sanding until you get the right contour. Spray primer filler and sand until all the imperfections are gone.

This is really hard to explain so if it doesn't make since just ask questions.