I plan to run 15mm in the front if I keep my 19 OEM's. The rears with the 19 OEM coupes are fine, If I wanna run a bit more aggress I would do 5mm. 25mm if you want a really aggro front, but you gotta make sure you balance the aggro in the back or it might not look so good. 25mm is gonna be really aggressive.

If you plan to get aftermarket wheels in the future, save your money and don't get spacers. Unless you really think you're gonna get high offset wheels.

Those H&R that you have, look really good with 20's. Look at ttrank's old pics before he swapped them out for coilovers.