If I took the cat out of my truck will it hurt it in any way? I know in the Army we don't have them on any HMMVs.
I don't have to worry about emmission laws my state doesn't have them.

The first thing you need to do is open up the exhaust. Start with a NEW 3" Downpipe off the turbo. What a lot of guys do is run straight exhaust from there...3 or 3 1/2 inch is best in my opinion...I went with 4 but the clearances are too tight between the bed and the frame, and it vibrates a little from time to time. Check with the local laws for your state to see how legal it is. If it's not, simply gut the cat and make it look like there's one there...you didn't hear that from me though.

The truck isn't too loud, because of the restriction the turbo causes...it'll have a nice, deep growl to it when you get on it...):h

Physically yes; legally no, even if state doesn't check, Feds can and will prosecute if caught so will most states if they know what they are looking at, HD 6.5s don't have them.

.......SNIP
The truck isn't too loud, because of the restriction the turbo causes...it'll have a nice, deep growl to it when you get on it...):h
I've got a straight 4" on mine, and it has a deep growl wherever I drive it. You wouldn't believe the number of people that try to get up next to me and "play". I attribute most of that to the intimidating way the thing sounds.

The sound of the turbo through that 4" pipe makes it worth putting up with the slightly obnoxious growl all the time though! :exactly:

I tried runing the truck without the cat but it didn't help the problem it had

Did you ever replace the timing chain-set?

What about the injectors?

The cat actually presents a very small amount of resistance to the flow of exhaust gases. Removing it may not reduce backpressure significantly. Replacing the exhaust with a cat-back system will do much more to improve the engine's effiency and power. I put on a 4" cat-back system and it really woke up the engine. I also replaced the downpipe with a 3" version, as well as the cross-over pipe.

I think the guts fell out of my cat when I replaced the exhaust components in front and behind it. Whoops!!! :-)
Jake

How do you go about removing the guts out of a catalytic converter?

either a hammer and screwdriver to chip it out, or a hammer and piece of pipe that will fit inside of it and take 'core sample' out of it

I just cut the exhaust pipe in front of the cat so there is absolutely no backpressure right now.