I am considering swaping out the factory exhaust for something a little loader and a lot lighter. I don't daily drive the car, but I also don't want something too loud. I was looking at the Mugen, but was wondering what other options I have that will fit my '07.

 

I'm not too exhaust savvy but I installed an Invidia.
Total install time is about 2hrs or less and the visual zing can't be matched.
Weight is probably half of the OEM and the sound (V3) is reasonably quiet if you want it to be.
If your not looking for the exoctic mega-buck system ,the V3 is worthy of consideration. If appearence is a low priority, shop one of the deals on the S2KI forum.

 

greddy TI-C nice dual exhaust with titanium tips

 

T1R, Mugen, Amuse, HKS....etc. but not J's.

 

Mugen will probably give you the best sounds without drone. It also looks beast.
The only down side is that it is $$$.
The T1R 70 or 63mm are both really nice exhausts. The will save you weight and sounds really nice.
The Invidia has a really nice price, but will drone pretty bad.