Since I put my duals on I angled the pipes down a little like unreg. said and I have had no problem with nasty build up. Plus it helps when there is water in the muffler the water comes out easier and doesnt blow **** all over my truck

 

Another out the side here too... I don't notice anything on the rim at all. The back rims are great... its the front rims that are a pita to clean. no more napa mid grade pads lol.