I need to find a 4" inlet 4" outlet chambered muffler like the powerstick kinds. I want to run the Flowmaster 3" inlet 4" outlet merge to this muffler and then a turndown off that. Anybody know where I can find one? I google'd a lot and only saw 3" versions.

Like this but bigger,

 

If no one can find the 4" version of the muffler above, what does everyone think about these 2 mufflers:

http://www.summitracing.com/parts/BOR-40741/
- or -
http://www.summitracing.com/parts/GIB-789600S/

 

Go with the Borla.

 

Try looking into diesel mufflers? I've seen it done a few times but out of the two you linked, the Gibson has the price but Borla has the rep, tough choice!

 

That Borla is too large in diameter to fit. The Gibson will fit but I'd never heard it and for that price, I think you'd want to hear it first!