Cummins 500 Exhaust mods?

[roaming]

On my pickups (Powerstroke and Cummins), the first order of business has been to go to a 5" exhaust for heat reduction and better flow since the manufacturers typically undersize them. Does the same principle hold true for MH exhausts? The TS that we're picking up has the Cummins 500, but I can find nothing on the internet about any exhaust work done other than hanger bracket repair. Is this a common scenario, or are the exhausts already properly sized?

Thanks!

[augar boy]

I have the 500 cummins and have not read anything on upsizing of the exhaust. However, on my engine, the exhaust comes out of the turbo on a three inch and increases to a four inch on the exhaust. This might have helped the power issue but I don't know as it has plenty of power in my opinion.
Heat is the big problem I have, apparently the larger size has made little difference. In the heat of the summer it is unbearable in the back of the coach with all the ac's running and this just heats up the rest of the coach.
I am going to pull the exhaust off and wrap it with an insulation made for exhaust and that is suppose to reduce the heat output by as much as 50% to 60% and send it on down the pipe and out.

[roaming]

Interesting, I wonder if someone makes a 4" flange to replace that 3". That's a common problem on pickup trucks, but it's due to clearance issues around the firewall and you can go to a 3.5" but not much more. It would be interesting to see how the EGTs change with the wrap change, and a diameter change if someone makes a larger flange.

[jtovo]

I just had my exhaust repaired for the second time, the 4" pipe coming out of the turbo broke off & the heat from the turbo burnt up several air lines.
The 4"does go to a 6" pipe.
Looking to find if anybody has had this problem & possibly figured out a solution. I have wrapped all the lines with fire resistant insulation in the path of the exhaust exiting the turbo, but I still had a couple of lines melt this 2nd time.