PITA swapping out spacers.

ok so im going for 255's up front and 285's rear. i wanna drop the car by 1.2" and also wanna add spacers to my stock rays. can anyone recommend me the best spacers and should i go with 20mm front and 15 back? i want the car to have an aggressive profile but also retain handling and performance. dont just wanna go for looks. thank you.