Has anybody had a dyno of before and after installing an aluminium driveshaft on the n/a 4.0. I know that there is no HP "gain" with the driveshaft swap but is there some more HP from the motor that are going to the rear wheels? Is it worth it?

 

Yes! I had a dyno done before and after I had the ph driveshift installed. No change in gain, but a hell of alot better on the highway at high speeds. Before I had the ph sd I had alot of vibration at high speeds from my ds and it seem to be a little lazy getting up there. But now its very smooth going from 80-110, just punch it and go's

But the gearshelp in that department, 3.73 and lose about 2-3hp
Maybe this will help you to see if the driveshift is for you.