Well since I have the fiberglass on my bomex side half done I need to trim some of it to fit. The part I need to trim is where the splash gaurd would normally go and where the kit needs to go around. What would be the best way to trim down the side skirt without it cracking?

I use a dremel... it comes with a small drill bit to get a starter hole and then get one of the pics meant for sawing threw plastic and tile and crap liek that, they have a bunch of them, its not sharp enough to grap and tear, you can actually stick your finger on the bit while its moving and it wont do anything, but it will go through fiberglass very nicely and very cleanly, only problem is LOTS of dust