Stelling headers with the 6" dry tails. When you look up inside it looks like a gattling gun with a bunch of round tubes. Who made it and can I pull it out??

They're welded in your Stellings, you could pull them out but they're integrated into the tail, you'd more than likely risk damaging the tail removing them. Keep em or run new pipes...Besides, they aren't all that quiet...

IMCO I believe makes the same style so does Borla...

Yours are 6" because the pipe has to be jacketed due to the fact it is dry, hence the extreme diameter...