I have had the luxury to personally work on numerous GTs and attend many GT events. I have heard all of the GT exhaust systems first hand and I have discussed the unique traits of the different systems with many owners. My personal favorite is the Heffner unit. It sounds absolutely awesome - but it will not drone at cruising speed. It will save you more than 50lbs when compared to the stock exhaust system. Factory catalytic converters are retained making this a true cat-back performance exhaust system. Cool Tech worked with the Heffner team to develop an exhaust for the Rear Bumper Delete kit and this outstanding product is the result.