Gutted Convertors

[87street]

Well here is my situation I'm going to face with my exhaust. I have 1 5/8 inch BBK full length headers to base my set up on, I'm taking it to the Midas my dad works at to have it installed, and he says that he has to put convertors on my car but that I could always gut them, and I'll get a good sound out of it.
How much difference is there in an exhaust set up with gutted cats and a 2 1/2 inch h pipe, to no cats and a 2 1/2 inch off road h pipe? I Planned on running this set up with either Flowmaster 40 series or the Super 44's with turndowns. Will it sound basically the same? Just as loud hopefully?

 

[FrankenStang]

I believe gutting your cats is illegal.

 

[Mustang5L5]

It will pop more as the air rushes around the empty cats.


WHy not run high flow cats? There will be barely any difference in power, and your car won't smell like an Exxon tanker tipped over on it.

 

[Gearbanger 101]

Contrary to what your Dad may think, gutted converters sound like ass! They sound tinny and hollow and more often than not, they leak afterwards.

Please, oh please don't be one of those guys that screws up a perfectly good set of cats. Its more work chopping them off, punching them out and welding them back on then it is just to build a complete O/R H-Pipe. Or, you could quite being such a cheap skate and buy one....they're only about $150.

Not to mention running around with no cats isn't worth the headache!!!

 

[66sprint6]

They absolutely dont sound ANY different at all. I went from catless H-pipe to addin gutted cats to the SAME h-pipe, nothing else changed and the sound is absolutely 100% the same, no popping, nothing at all, sounds just as amazing as before. My car passed sniffer with the catless Hpipe but didnt pass visual (duh) and since thats the important part when it comes to the environment I decided to NEVER fail visual again lol. Do it.
Matt

 

[Gearbanger 101]

They absolutely dont sound ANY different at all. I went from catless H-pipe to addin gutted cats to the SAME h-pipe, nothing else changed and the sound is absolutely 100% the same, no popping, nothing at all, sounds just as amazing as before.

I disagree. I too did the same thing and the resonance was much louder at cruise speed. The exhaust pulsed don't reverberate into a hollow cat in the same manor they do with strait pipe and it increases the dreaded "exhaust drone" substantially. Especially when you're running chambered mufflers. I kept it that way for about a week before it drove me batty and I went with a high flow X-pipe instead.

 

[87street]

Thanks 66sprint, that's all the motivation i need. I just wonder if it hurts performance at all? I would figure not, but if it does it's not by much i'm assuming.

 

[66sprint6]

Thanks 66sprint, that's all the motivation i need. I just wonder if it hurts performance at all? I would figure not, but if it does it's not by much i'm assuming.

Nah, i wouldnt imagine it would at all. Didnt feel, nor hear ANY difference WHATSOEVER, and Im STILL runnin em, been runnin em for a month now and its all the same. I can see em, thats the only difference. I got 40 series flows...so that hollow tin sound is normal LOL, and I love it. You wont regret it, and youll NEVER fret whether itll pass visual ever again.
Matt

 

[87street]

Rock on.

 

[Mustang5L5]

I noticed a difference. I ran a straight off-road H-pipe, a gutted H-pipe and a stock catted H-pipe on my car at some point. I could tell a difference in sound between the pure off-road pipe and the one with the gutted cats. I also have 40 series flows, and the gutted cats definitely popped more when i let off the gas and had the RPM's drop.

I now run the stock catted h-pipe as i got sick of the whole "no cats thing". I plan on putting a true high flow catted pipe on soon.


87 street, you got two different opinions in your thread, from the sounds of things though, it seems you already had your mind made up anyway.

 

[87street]

No, not really, just looking at the answer that is the most optimistic, lol. I'm going to try this out though, I doubt that trying will effect in a negative manner, I suppose if i dont like the gutted cats I can always go without them

 

[Stroked N Blown]

He picked the answer he wanted to hear. O well

 

[strtrcr50]

Enjoy smelling like exhaust..

 

[66sprint6]

Thats so wierd cause my coupe doesnt pop at all. I HATE popping on decel, and would definitely tear that crap out from under my car if it did it, but Im not hearin any popping from mine. Wonder what thats all about...must be a "try and it and see" kinda deal, some will pop some wont.

As to the exhaust smell...yup, definitely smell like exhaust but Ive never owned a vehicle with cats on it in my life so im used to it LOL

Heres the exhaust with Catless Hpipe

NOCATS
View attachment 280326

And I just ran outside in the rain to get this video with gutted cats

GUTTED CATS
View attachment 280328

Hope that helps, if it means anything the cats are placed right where the Hpipe bends from the down pipe (header connection) to where it flattens out under the car. Ive heard that placement of just about ANYthing in your exhaust can change the tone etc...maybe thats why mine doesnt pop or sound bad.
Matt

 

[Deleted member 87397]

Thanks 66sprint, that's all the motivation i need. I just wonder if it hurts performance at all? I would figure not, but if it does it's not by much i'm assuming.

A high flow set of cats isn't going to hurt performance much and you'll still get decent sound. Gutting the cats can actually hurt performance a bit because as the exhaust enters the empty chamber it's velocity slows down. You'd probably never notice it, but it's possible.

 

[skunk21]

My car came with an off road h-pipe, didn't like the exhaust smell and MA for the most part does a visual. I had a custom h-pipe made with magnaflow hi-flo cats installed. smells better and it feels the same powerwise and sounds just as throaty as before( i have flows).

 

[66sprint6]

My car came with an off road h-pipe, didn't like the exhaust smell and MA for the most part does a visual. I had a custom h-pipe made with magnaflow hi-flo cats installed. smells better and it feels the same powerwise and sounds just as throaty as before( i have flows).

Thats prolly the best way to do it if you have the coin for sure. If im walkin around the car while its runnin ill end up stinkin from it, but drivin it most of the time doesnt make me smell too bad. Again Im used to it, but if it became an issue Ide spring for a set of high-flow cats in the future. If your just lookin to pass for cheap and not hurt anything, gut em and go!!!
Matt

 

[Strype]

Ran gutted cats for years with not much difference. A little bit more tone and that's all. No popping. Gutted them while they were on the car, then had the exhaust welded back.