Has anyone used this setup?

What problems, if any will I have?

I don't like the gap 19" rims leave on the rear and I do not want to void my Nissan warranty by lowering the car with performance shocks and springs unless I really have to.

 

Yeah there have been a couple people to do this. IMO it looks a little funny, and I would just go 20"s all the way around if you are going to use 20s. Also, I dont think putting 1" drop Eibachs voids much if any of your warranty.

 

19" front and 20" rear is GHETTO. That is for muscle cars. The Z will look much better with same size rims front and rear.