Hang on.. wait, wait, wait!
You're saying a 18X8 +38 needs a wide body kit!? You building a hover craft or something?
Can mods merge this with the rims thread and get this dude to have a read of it first.
the front wheels is 18x8,but the rear is 18x9 or more
At 18x9 +38 you will have clearance problems with suspension before you have any problems with the guards, but even still you wouldn't need any widebody kits. Definitely go through the other rims/offset threads as soon as you can.
Oh in that case, may I suggest a 100mm over fender or even some custom fibre glass work.