I must desagree with 100% of what you said. The Greddy Evolution is a piece of art, unlike ALL or most of the other Exhaust in the market the Greddy is designed to have a offset do it does not"hang" like most of the competitors muflers creating the Cheap Honda civic street $50 mufler almost dragging to the floor.
As far is performance I believe that it play 3rd in the 11 shoout competition and second or third in torque and first in sound, indeed it was the quiest.
As per the weight, yes , you might found other exhaust that are lighter but power wise you would not find much of a diference, maybe 2 or 3 hp more.
Greddy have been making great exhaust systems for many years, their quality is second to none so honestly I must desagree with your review.
Great looks, great sound, great price, great performance= Greddy Evolution fat 81mm piping!!