Alright guys I have an 04 Silverado reg cab 5.3 v8.

I currently have a flowmaster super 50 muffler on the truck and I have been running it for about 3 years. Im starting to look at maybe installing the super 40 muffler on my truck. Would the sound be a lot more different? Would it be worth it? And also how is the interior noise?

 

The regular 40 is a bit louder than super.

To make sure you don't get resonance, just have the exhaust tips dump out the back or sides of the truck.
Don't put the tip straight on the muffler or you'll likely get that's annoyance.

I think the 40 is the perfect mix between volume and beefy rumble.
Its not loud enough to wake the neighbors at idle, but when you step on the gas "HELLO!!!"