It was very noticeable in power when the headers were paired with the X-pipe. I had them both installed at once so im not sure how they are separately, and I haven't had time to get exact dyno results. But when it comes to sound...It can get LOUD! I have
Magnaflow Competition Axle Backs so it has a very deep muscle car sound to begin with but after the LTs and the X-pipe its a completely different monster. It took some getting used to at first but Im in love with the sound. Its a deep, raspy, muscle car sound that Ive had many compliments about from other car lovers and from people just sitting at red lights. Cruising around town its not that bad but once you put your foot your to floor it sounds like a racecar
hope this helps some, Ill answer any other questions that I can