You get what you pay for
Where do I start. I love my Borla ATAK exhaust! Zero drone. Loud roar when you punch it, and smooth not over bearing sound when you're cruising at 70mph. I call it my sleeper exhaust. It's loud, but only when you want it to be. You won't wake the neighbors( unless you're reving your engine). it took a few days for the computer to relearn the exhaust, so no resetting. I've noticed faster acceleration and better fuel economy because of it. It's a little expensive, but totally worth it.
Flow Master axle back outlaw exhaust
I have a 2017 Dodge Challenger R/T and I bought an exhaust for 2015-2016 R/T. The exhaust is different so I had to come up with a bunch of modifications to make it fit correctly. This was my fault, because I did not want to wait until they made an exhaust specific to my car. Sound is great, did not see an increase in torque or overall power.
Headers look great,good welds, smooth bends. Feels solid. Instillation was not easy,but with a lift and a fiend to help it wasn't terrible. Combined with CAI, cat back exhaust they really woke up my 2010 Challenger 5.7. The engine spins up much quicker than with stock manifolds. Sound is about the same. Not noticeable louder inside. No dyno numbers but seat of the pants feels like 25-35 more horsepower.