I am thinking of putting stacks on my truck but was curious as to how hot they get. The reason I am asking is I have an auxilary diesel tank in the bed behind the cab that I use to fuel my dozer. Does this pose any danger to put the diesel tank within an inch or two of the stacks? I do tow heavy, 30 ft gooseneck about 8,000lbs plus dozer around 15,000lbs give or take, with the straight pipe now the sound doesn't really bother me. If I run straight stacks is it going to run me out of the truck? At most I am pulling this load 3 or 4 times a month the rest of the time I am running empty.

 

I just put 5" stacks on my truck last thursday. It is pretty loud but I think it sounds good. I have a straight 4" pipe running through the bed into a 6x6 square tubing and then to my 5" turnout stacks. The stacks don't get real hot but the 6x6 tubing does but I don't think it would melt anything if it was not touching it.

 

I have a single 5" stack within 2 inches of my 45gal. Handy fuel and tool box. Shoot, you can hold you hand on the pipe for a long time before it gets too hot. I seriously doubt you'd ever get the fuel in your in-bed tank hot enough to cause a problem.