Towcat why do you think the IDI does that and not the 7.3 PSD? It can be kind of cool between gears and zipping around but.........
The 90 F250 was 7.3 IDI, Banks turbo 5spd.
We used to tow horses the the high sierra every weekend. Coming back 5,000 ft elevation change on twisty roads with precious live cargo. Using the gears (usually 3rd) dropping down mile after mile that "jake brake" effect wasn't funny. Didn't do it with the Banks muffler but it HAD to be straight piped right? 3x louder going down grade than up lol! Thought the horses would be deaf... Had to push in the clutch after a half mile of increasingly louder resonation. That would start the cycle over again.
Weird how the 6.9 / 7.3 do that.