G'day guys.

I have a EF XR8 and have just recently fitted a vortech blower. Now the problem is that when I booted it from a stand still it will rev out and then change gear at 4500, instead of around 5000- 5000rpm. When it does change it will take its time doing it too, so it isnt a smooth transition but a indecisive moment.

I do think the transmition maybe slipping, it also is indecisive in changing down as well. the box is now 138k old , hasnt had too hard of a life, but has been used.

Now Would the box need to be recond/replaced? or would it be the torque converter? Also what would be the culpirit with the kick down?

are you running a shift kit? with a blower you will need to run a shift kit otherwise you will fry the auto.
As for the shift points, the TCM determines the shift points by road speed, rpm and throttle position. Providing the TPS for the auto is set up correctly it should hold out till the redline under WOT.

No shift kit being used at the moment, guess thats the next step.

Pm Sent.