Well I've been doing some research throughout the past few weeks and have decided to gut my cats. Before I rip my entire exhuast apart I need to know the inside diameter of the the cats. I plan to run a 2.5" hole saw and 2.5" straight pipe through the cats. Can this be done or are the cats 2.5" outside diameter? Will I need to use 2.25"? I need to keep the cats for visual inspection, and I dont want to be bothered switching y-pipes every year. Thanks for the help guys.

 

ttt...somebody has had to have ran a pipe through there cats before.

 

I think you are making this harder than it is. Take a sharpie and draw several lines perpendicular to the weld that hold the cat on. Sawzall the cat off right next to the weld. Take a long rod and beat the crap out of there. make sure its all gone. line up your marks and weld back together. Stock looking cats with no restriction

 

with gutted cats and a tune for 02 sensors...is there any way to fail emissions?

 

only if they use a sniffer, but that's only in the strictest of states that require that.

 

Thanks for the pics, they helped out a lot. I think I will cut the welds right off, I still would like to run a pipe through to eleminate any turbulance but I can make the opening whatever I want with a die ginder. Thanks for the help again I really appreciate it. I'll take pics Of what I do and see how they compare.

 

What's a sniffer? I'll have to look into that or if anyone is from Maryland....chime in here.

SBChvy, I was wondering about the turbulent flow as well. Anyone else have opinions on this?

 

Heck i just gutted mine like Slowec did.... and we dont have emmissions stuff around here... it is just alot easier to wack one end off and clean it out and then just weld it back together... after a few months the welds will disguise theirselves in dirt and stuff..

 

Well I finally got to gut them yesterday, all went extremely smooth. I decided to do the same as Slowec did, the opening through the cats is only 2 1/4". I started out by pounding a long 1/2" bolt through as a pilot, moved up to a 3/4" bolt with nut on, then up to a stack of 2- 2" diameter wrist pins from a tractor motor, and finally just used a long screwdriver to scrape the sides. Took about 3 minutes per cat. I love the sound that the truck has now, it is a lot more throaty but highway speed is still quiet with no drone/resonation. I feel no difference in power, but have yet to plug the HPTuners into her. Thanks to all that have helped out.

 

How bout a vid or sound clip?