I am going to be putting on a 5" turbo back system on my truck and I am debating on what to do about the Cat.

I have to have emissions here, but from what I understand it is just a visual check for the cat and that the truck should pass without the actual cat on there.

My question is should I take the time to hollow out the cat and run the 5" through it or leave it as is and just weld the cat into the new 5" system?

Are there any gains to be had by removing the cat? Are they really that restrictive?

Also has anyone on here passed emissions in colorado with a hollowed out kitty?

 

My muffler shop cut the cone sections of the CAT back to make a 5 inch diameter, then welded her up in place...

 

That is exactly what I am thinking of doing. What do you think of the sound? Did your egt's drop at all going to 5"? Do you regret at all doing it that way or do you wish you would have gotten rid of the cat?

 

love the sound, running an aero 5050XL for a muffler. EGT's didn't drop enough for me to notice. With the upcoming smog checks starting next year, I am glad I kept the CAT. The turbo did seem to spool quicker with the 4" exhaust...yet I do love the deeper sound of the 5 inch exhaust. I am also running a 5 inch down pipe...

 

I hollowed mine out just enough to slide my 5'' through so it looks like I have a cat still and has the correct sound when tapping on it. With what I have for a muffler (fullspectrumperformance-ebay store), I like the tone it produces and I don't have any 'drone'.

 

This is the other option I am contemplating. I don't know which way I want to go. Did you notice a significant drop in EGT's at all? Have you had to pass emissions with your setup?

 

Remember, without the CAT, it smells like good ole diesel exhaust, with the CAT it smells like propane exhaust to me. There is a distinct smell, no need to tap the CAT...

 

I'm almost leaning towards just leaving the cat in, especially with all the emissions stuff that is becoming ever more prevalent.

 

I've done alot to my truck as you can see in my sig.. Trying to remember if it really did make a diff. in temps. After I changed the whole exhaust, I loaded cl into the pmt I had and that made higher temps. I'd have to say that it did drop temps by 50-75* by loosing the cat.

It's always been a thing with me on exh., if there's not a free flowing system then I change it so it is a free flowing system. So with a cat involved, there's some sort of restriction, have you ever tried looking through a cat?? Barely see any light through it.

I don't have any type of inspection, yet.......but if these tree huggers have their way.....alot of trucks won't even pass the visual just by popping the hood. The cai isn't carb verified. Just with that, fail.

 

Hmm decisions decisions.

Akita I don't suppose you have a sound clip do you?

 

no i do not....yet from YouTube...

http://www.youtube.com/watch?v=Vih2B-RGOM4&NR=1

http://www.youtube.com/watch?v=JYGix...eature=related

http://www.youtube.com/watch?v=iDTTO...eature=related

http://www.youtube.com/watch?v=XzbqyxYeQcc

 

Well if you happen to get one anytime soon I would love to hear it. I just can't decide what to do about mine.

 

Although I still have the stock 4", I just cut the cat off and replaced it with a straight pipe and SS band clamps. Same for the stock muffler which now has a MBRP. I love the sound of mine and I have little drone and see a 50-75 degree drop in temps from cat removal only. I still have the cat, that way if it needs to go back on for inspection, I'll simply remove straight pipe and stick the cat back in with the same band clamps. 10 min job. Maybe this gives you another alternative.

 

My buddy straight-piped his '05 and claimed it ran lousy as well as droned him to death. Next was the 5" Magnaflow ss turboback. He's young and this one drones him to death also. He wishes he had the stock exhaust back with a low restriction muffler like mine. Emissions are coming and he's going to be reinstalling the cat to his Magnaflow setup which will legalize him as well as quiet things down.

 

Well I installed mine last Friday and I cut the cones of the cat back to fit on the 5" system and reinstalled it. I am happy with the sound and the way it performs. Runs great and Egt's are down a little, not much but a little.