Hello ,
My friend has a 1997 2500 auto 12 valve . He has a 8000lb 5th wheel trailer and says the gap between 2nd and 3rd gear is too much

.ie : the revs drop too much when it changes to 3rd gear .
I said he needs more power and torque

.
I have told him to get gauges for EGT , trans and boost

.
Would a TST power kit make it pull better and be safe for the motor ?
We are in Australia . The local shop tried to sell him an Edge EZ .
Thanks,
Graham.