Adding an aftermarket exhaust system to your vehicle will not void your warranty. If your new system does not cause any damage to other components on the vehicle, then your warranty will be fine and remain intact. However, if a problem arises that the dealer can trace back to the aftermarket system you installed, then your warranty (or a portion of it) can be voided. For instance, let’s say you installed a full header-back aftermarket exhaust system, and the catalytic converter failed afterward because of something to do with the design of the aftermarket system. The warranty would be voided, and you’d be paying for a new cat out of your own pocket.
Does after-market cat-back exhaust system really improves the horse power and torque in the 6.4 liters? If so, which is the best recommended?
The factory exhaust is pretty efficient. If you have the active exhaust mode, you already have great sound. Also, I wouldn't expect a significant increase in in horsepower or torque. I wouldn't waste my money on a cat back system. The primary reason owners spend $1,000 or more on a cat back system is to get a deeper, more throaty exhaust sound. But even though the sound is the number one reason many buy a cat-back exhaust, manufacturers claim wo more benefits- improved exhaust flow (exhaust flows more freely because of the cat-back exhaust system’s larger diameter tubing and less restrictive resonator and muffler) and increased performance (because of the weight savings). The best back system is purely subjective. You should listen to sound clips to see what you like. Some of the popular brands are Corsa, Borla, Solo, Flowmaster, Zoomer, Magnaflow and Hurst Elite.
I upgraded to a magnaflow on my ram 1500. Has anyone upgraded their scat pack and if so what are your impressions.
CATBACK should have no impact on warranty. The cats on the scat are single digit loss. So i say they are great. Minimal gains to go aftermarket. I put a Magnaflow xMOD on my scat. Here is a quick start and couple of revs. https://youtube.com/shorts/YvMEAa8bg4o?feature=share