I think if you have 19"s you should get a set of GiroDiscs... makes the car looks 10x more agressive.
They're doing a great special here:
http://www.championmotorsport.com/product-p/731.htm
All that money spent on trying to make the car go fast is really if you have the spare money, as they're pretty low on bang-for-buck ratio. The only way to go real fast is a 3.6/3.8 swap or TPC Turbo.