I did mine in about 30 minutes and I have yet to have water or anything else "blasted" into the filter. Maybe you just cut the hole too damn big:dontknow:problem with the CAI is the position of the pipe, you have to cut into your Inner arch which leaves a nice hole for all the water to be blasted through right onto the filter.
Anyone who says they fitted one of these in an hour hasn't addressed this problem so i guess lives in the dessert with never any rain.
When i had one on mine i went to the scrap car yard and looked around and got an arch off some car with a bulge in it cost me like £2 ($4) for the arch.
I went home cut out the arch and glued and pop rivited it to my arch, sealed it up real good and looked like it belonged there.
Lots of water or not, with a hole there its gonna put loads of shit on your filter reducing flow.
Loved the injen, only changed it to get more power.