Hello my fellow IS owners I'm turning to you all for a little advise. Recently I've been wanting to add a rear spacer on my car as I want my rears more aggressive (Fronts are good to me as the camber kit brought the tire flush to the fender). Can you guys take a look at the picture below and let me know what size you guys think would for me without having to cut/pull the quarter panel. I don't mind rolling it but I don’t want to cut or pull which size do you guys recommend 10, 15 or 20mm?

Pictures for refference

 

20m and roll it , looks good bro

 

What offset do you currently have in the rear? Looks nice.