The 6.2 is just a bit lighter than a 4bt, the 6.5 is about the same weight as a 4bt, the 6.2 was naturally aspirated and the 6.5 was both natural as well as turbocharged. The 6.5t made a bit more horsepower than the naturally aspirated versions. As far as dual side pipes, well with a turbo charged engine you only have one exhaust outlet regardless if it is a "V" block or an inline block design. But a diesel swap will eventually led to much more than just a engine swap. The entire drivetrain will most likely need to be upgraded eventually. I have a 4bt TJ and I have broken several parts in my built front D60 including the Detroit locker.
x2 on the 4bt swaps.com website, they have a ton of info there on all types of diesel swaps.