For now I am thinking of keeping my stock wheels and adding 15mm spacers to accommodate my soon to be put in Akebono's.

In the spring I will be buying PS2's (225/50/18), do you think this will offer a comparable performance to a 19" tire with a smaller sidewall?

 

I doubt you would ever notice much difference on the street. It all comes down to the tires.

 

it shouldnt much difference except for ride comfort. doesnt the 09 G37 sedan come with the Akebonos with the sports package