Okay so I pulled off my guards today and looked into this whole 'trimming' thing.
If you want proper fitment and want to run the track width/offset that will fill out the fenders you WILL need to trim the car or else your tyre will foul/scrub the car on full lock. This is because the extra track/offset will increase the outer turn radius of your wheel/tyre and thus foul the piece in question. I know some of you will already know this but I thought I'd add it for anyone that didn't.
If you just want to run standard wheel sizes and offsets like 8/8.5/9/9.5 +38 & > etc you don't need to cut. You will however see the pieces in question sitting behind your new fender which are pretty ugly. See pictures A.
From what I make from the instructions that came with the fenders is that there are two options. Option A is trim off the tabs and option 2 is completely cut off the whole section and weld a cap back on. Personally I will be simply cutting off the tabs hoping this is going to give my wheels enough clearance but if it doesn't I'll have to move to plan B. See pictures.
