Pick my mufflers

It's been too long for me to be sure, but years ago my dad and I built a 69 Charger with a 440 for my brother and I'm pretty sure the exhaust shop put Magnaflows on it. They were okay sounding, didn't quite have the real deep rumble. The main thing we didn't like about them is when you wound it up it sounded like they just couldn't handle the flow. My dad compared it to blowing on a trumpet too hard, it didn't keep the tone all the way through the rpm range. They sounded nice at idle, good and mellow, but sort of "whooshy" when wound up. Then again that was also on a big block, so it might be a bit of an apples to oranges comparison.