Greddy Evo......hands down!!!
it's very quiet, you gain a little more sound on the low end, but it's a deep throaty sound, and on the whole, the system is pretty damn quiet. it's a great system.
and i know your worried about the tip size.....so was i. however, i bought it from a friend (thanks jeff

), and given the choice between paying $700 for a new system with a small tip, and $300 for a used system with a big tip, i couldnt resist. however, i've grown to love the greddy evo tip. although 4.5" sounds really big, it fits so perfectly into the bumper cut-out that you dont really notice how big it is......it looks great.....and when it's polished.......WOW!!!
i think the Evo is the best choice