I built mine and welded in a cross about 6'' down to stop beer cans. Sure enough, the 1st day I had em on one of my smartass buddies tried to put a can in em, he was a lil disappointed when it didn't fall in. I still haven't built a shield for mine so trash rolls under my toolbox and melts to em and stinks purty bad. But overall, I love em
You lose bed space, if you haul shit the stack gets beat up by stuff not secured in the bed, depending on where the top of the stack sits you get soot on the cab, if it sets above the cab you still get soot everywhere and down the side of your bed after a good morning dew, etc. Also the in cab noise depends on where you put the exit at so just be ready for a noisy bitch if it's below the cab.
I loved mine. I had 5" duals, then a 6" single, which sounded the best. The only reason I took it off was because it was turning my camper black. The soot from it was terrible, especially if it was raining.