the ls has a different firing order than the old school small blocks and bgblocks. i do like the sound of them with an x pipe and flowmasters though. ever since i was a teen my favorite mufflers on cars has been flowmaster chamber mufflers. they sounded amazing on the old 5.0 mustangs back in the day i thought as well.
Yup, does not get much better then a 5.0 with 2 chamber Flowmasters. Especially if it has a cam in it. I don't know why, maybe the firing order? But it sounds better then any other old school small block.