I've just installed duals w/ X pipe on my 4.0/v6, last week and I notice that when I'm on the highway the car feels like the tranny is not going into that last gear doing 70@2000rpm

Then when I'm doing 50 the tranny go's into that last gear.

I don't remember the car doing this before the X pipe, I know the 3.73 gears makes the car rev high but the tranny would always shift to that last gear at some point.

Has anyone ever experience anything like this after they put on the X pipe?

Thanks for any help you can give me.
Denny