MTL_Z28

Hello,

I was going to go to my friend's exhaust shop to install my 3" cutout (non-electric)on my single cat OBD1 car and I was wondering where the best place to put it was (the car is stock right now).

At first I thought I could install it in the place of the catalytic converter, but I figured that would not be such a good idea since the sound would make my car a cop magnet and if I had no cat, then I could be in big trouble, and also I was not sure about the diamater of the piping would make it possible to do this anyways.

So now my friend tells me his dad can do what he does with other peoples cars and simply "clean" the inside of my catalytic converter ( ) and then install my cutout right after that on my stock exhaust, so at least it looks like I have a cat. So my question is could there be any problems if I run my car this way? And will the noise be too much for me to tolerate (some people say it's better to install it towards the rear of the car).

Thanks.

Stoopalini

Is there room to install the cutout where the cat is, then reattach the cat to the back of the cutout? This way, when the cap is on the cutout, you have a cat that is doing it's job .... but when you take the cap off the cutout, it's dumping out before the cat.

My $.02

Thomas.

MTL_Z28

Good point. I hadn't really thought of that. The thing is, I was wondering about the internal diameter of the stock exhaust and cat, will it be possible to do what you're proposing with my 3" cutout? (in other words cut out a section in my stock exhaust, relocate the cat backwards and then install my cutout right after the stock Y pipe and connect it to the cat)

Stoopalini

Yes, it is possible. Any good exhaust shop should be able to weld all of that together with no problem.

MTL_Z28

But with the shape of the stock exhaust, I don't think it's possible to do this without cutting out 2 sections. 1 section for the cutout right after the stock y-pipe and another section for the cat behind the first section.

I think I'm just going to put it in place of the cat and run it closed most of the time. Since my car is OBD1 and has no after cat 02 sensors it shouldn't cause any codes right?

Stoopalini

Removing the cat should not cause any codes on an OBD I car. You should be fine as long as you don't have emmissions testing up there.

Thomas.

Z06Z28

I would keep the Cat on it cuz you wanna pass emissions right? I wouldnt even mess with that Cat, leave it be. Let me tell you where I mounted my Cutout and what I noticed since you are wondering about performance. Keep in mind, my car is stock and have headers & cai when I describe my performnce gain. And yes, they cut a piece of your exhaust off and replace it with the Cutout flange. I would recommend having a shop make you a turndown flange so you dont heat up your floor panel. Cool idea to have them weld the bolts of the turndown flange to the Cutout flange! It's easier to get the nuts on and off..or else your under the car dikin around with two wrenches unless you use locking washers.

This is what I noticed when I messed with a Cutout:

Welded Cutout after the Headers but before the Cat:
*noticed and all around diffence but very good pedal response and acceleration at freeway speeds.
*very loud, people will hear you a mile away. Cool huh! Not a good idea for an everyday driver in residential or public roadway. Freeway, ok! Manual plate or e-plate would be recommended.

Welded Cutout after Cats but before muffler:
*noticed a good low-end pedal response and acceleration at low to mid speeds.
*at first the sound is hard to adjust to but you become tolerable of the sound once you drive for awhile. You have a single cat so it might be a tiny bit louder than my dual Cat. I use to drive around with it open all the time and I drove past cops all the time. This option may be what your looking for.

Right now I'm running ORP's through a Flowmaster muffy and it sounds awesome. I havent opened my Cutout yet in a long time so I hope to hear my free flow choppy chop exhaust this weekend.

ARTIC_Z

mine is before the cat. and i dont think anything had to be moded.

MTL_Z28

That's the thing, there's no emissions testing here. I don't have to worry about emissions testing but I DO have to worry about cops. Although, around here, the cops tend to leave "the muscle car crowd" alone. It's the ricers they will go after and ticket without even a good reason.

For what you said about the performance gains, I'm worried that if I put it in the place of the cat that I will lose some low end torque since it completely eliminates all backpressure. And I know it's loud, but is the sound intolerable? Also I would buy an electric valve but they're like $170. Like I said I would run it closed most of the time but open it up at the track or when I'm out late at night

I'm worried also that if I put it after the cat that it justwon't be worth it. Also when I get more serious mods, i would like to be able to run open headers (I've got long tubes coming as well as some other stuff).

Z06Z28

No smog testing? Dang, I wish I can live where you are at!

Well, I described it the best I could so I can't help ya much further. How about you disconnect your I-Pipe from the Cat-Back and drive around with it off and that's what it will be like with a Cutout after the Cats. Better to find out that way instead of going through all this trouble and deciding that you dont like it and spent money on the cut and weld job. So drive around with your Cat-Back off and make a decision if you like that performance.

JJJ93z

i have a 3 in flowtech in place of my cat, but i also have aftermarket exhaust (hooker) it sounds awesome but can be annoying. i got a dmc elec cutout, and even when its closed it still leaks because of all those gases coming out of my headers/y pipe so close to the cutout valve. i am in the process of buying a new cutout and relocating it further down my I-pipe so the cutout stays closed w/o n e leaks. by the way stock exhaust dia. is 2.75 you can slip a 3 in pipe over it and clamp it with no probs.