high flow cats? reccomendations?

i allready installed a dynomax ss high flow exhaust......
was thinking about a hf cat.
worth it....? will it give me a louder tone?
and should i go hollow,,,or just higher flow?

emissions an issue?

emissions in my area isnt an issue.......
but if a hollow cat isnt gonna make it sound MUCH better than a h/f..then i would stick with teh h/f.
plus i dont wanna loose so much backpressure...that i could eventually damage my engine.

if you have the hf cat keep it, you compensate for removing the cat with smaller pipes so you dont damage anything, but overall removal of a hi flow for a steel pipe wont make much difference

High flow cats do seem to make a difference seeing the stock one is rather large and is used as a resonator in our exhaust system to take a little of the grumble out.

I installed one and man, it sounds nice. Especially at higher rpms.

But only replace it if your is having a problem or is broken. I only replaced mine because one the the internal biscuits came loose and was rattling.

What does the rattling sound like? It seems like some trucks have this hissing sound like a boiling coffee pot. I don't really know how to describe it- it's sorta like the electric motor sound the rear window sprayer makes on my jimmy. Is that related to the cat?

Hissing sound should be the fuel pump.

The rattling noise is a metallic tight rattle under the truck.