01 Silverado

Has anyone gutted the cats or heard of someone who has on our trucks??? I have heard some good things about it and some pretty bad things, just wondering if anyone has tried it. btw... i have the stock y-pipe, but I have a flowmaster cat-back.
Any suggestions would be awesome!
thanx, <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

graygmc

when you say gutting do you mean putting the cats back on to look like you have cats? if so then make sure you put the same size diameter pipe in the cats as you do for the rest of the exhaust. if you dont the bigger diameter of the cat into the smaller diamter exhaust will create turbulence. this is bad and you will lose power. but then you could just put the same size diamter pipe in the place of the cat and have no problems.

01 Silverado

What I mean is taking off the stock cats from the y-pipe and removing the insides of the cats.... so basically it will just be a hollow tube and have better air flow. I have talked to people who have done it and they liked it, but other people say not to do it. I have even heard that you dont have to take the cats off the y-pipe to do it, just take off the y-pipe and put like a metal rod in there to punch it out (doesnt sounds too believable)
any imput would be great!

BigKID

iTrader: (5)

If you do it, weld in a piece of 2.5" pipe in their place. Dont do the sticking a rod in and break up the honeycomb. You are also going to need o2 sims or programming to take care of the rear o2s.

01 Silverado

will the HP gain be worth the time it takes to do the project?? also... can the emissions test see that they are punched out?
thanx guys,
-Kurt

GREGGO

iTrader: (2)

Yes the emmissions test will pick it up. My suggestion is to pull you cats and weld flanges on them and where they were. Then fab up a spool peice to put in their place. That way you can take them in and out.

01 Silverado

Alright... thanx guys, I talked to a friend and he's doin it for 150... does that seem too high??

GREGGO

iTrader: (2)

Doing what for $150? Which way are you going?

01 Silverado

He is going to gut them out, and weld pipe on the inside of the cat then put it back on. When emissions time comes he will let me borrow a stock y-pipe w/ cats he picked up at a junkyard.
I hope it will all work out....
thanx for your help!
Fast 4.8... you mentioned a while ago thay you have seen my engine cover before, where did you see it at (besides my page)?

graygmc

yeah you will still need to weld a piece of pipe inside the cat if you dont take them off. cause turbulence is bad.