I'm sorry, but Flowmaster does NOT sound even close to the stock exhaust on an LS1. Maybe inside the car it is kinda quiet, but it definitely sounds noticeably louder and deeper outside the car as compared to the factory muffler. Of course, it is not quite as loud as a GMMG, wide-open Borla, or SLP Loudmouth either(especially at WOT). I'd put it somewhere in the middle.

Just go with whatever system sounds the "best" to you. And as said before, Flowmaster may not flow as well as most other aftermarket systems, but it will still flow better than stock.

Mike

2002 M6 Z28

 

Much thanks for all the input. Looks like you put a ding in my thought for American Thunder system. Got me interested in Magna Flow. Thanks.

By the way. Another dent to my thought on this system was that 2 of my friends reported a noticeable mileage loss. Got any opinion on this?

 

They must be driving harder.

As for the source of anti-Flowbee sentiment, its not just this board, my own example was classic car dragsters and thier own, proven experiences of .2 gains on the AVERAGE when throwing away the Flowbee and going with almost anything else, I still have mine along with a cutout.

Personal preference, chambered exaust, next would be a bullet style muffler.