A tinny sound is more a product of the muffler than the header.
Eg: A DC5 with TODA headers has a deep smooth, muted note.
Change the cat back to a Fujitsubo Power Getter & it changes to a loud sharp blasting sound... Still clean & smooth, but very different.
Change again to say, a Buddy Club Spec 4, the note changes yet again.
It's higher pitches with a metalic ring in the exhaust..

This is all with no change to the header or cat.
But for a truley deep rumble, you'll need 4 into 1's...
Or something similar.
It may not give you the best power output, but you'll get the sound you want.
Cheers

Adrian