I have a 05 g35x sedan. auto w/ 73000 miles on it.

For couple of weeks my reverse gear seem's very sluggish! Whenever I put the car in reverse, it seems to be getting wheel hop whenever i go above 3k rpm. or it just doesnt seem the same. Seems like the engine has to work harder to go above 10mph in reverse.

I did get all new 4 dunlop sp signature couple of weeks back.
also got a transmission oil flush with matic J.

What could the problem be?
thanks guys.