When is the last time the pan has been off the trans? Have you checked the fluid? Does it smell burnt or anything? It could be that someone left out a checkball or spring when/if the valve body was out.

 

Do you have a MIL light on for a transmission code? In some cases a transmission code will put your trans into a high line pressure condition. When this happens the shifts become much more noticeable and this might be your issue. If not I would assume that either your trans has a shift kit installed or the pressures in your computer might have been altered. HTH Vince B

 

only 14,5xx miles on trans, no MIL lights, no burning smell...
maybe the owner before me put on a shift kit or something..

 

I also think " high line pressure " have your tuner check it, as he /she may have upped it while tuning, or go to a good trans shop and have it scanned
Johnny

 

On my 99Z, the tranny was built and setup for hard shifts all the time, so just cruising from a light, on the 1-2 shift, the shifts were so hard that they literally knocked your foot off the accelerator.