C4ProjectCar

Well, I got my Corsa cat back, but when I went to install it I encountered two problems:

The cat, which I knew the previous owner had replaced, was a generic cat, not one specific to this car, so it has no plate with holes for the flange bolts on the cat back y pipe to go through. No problem, I thought, I'll just put it on without the flange bolts and fabricate something for the cat. Here's where I get to problem 2.

When I tried to put the new y-pipe on, I saw that it wouldn't fit. The exhaust pipe coming out the back of the cat is too big for the y pipe to fit over it. I'm guessing the muffler shop put on a cat with a larger diameter outlet pipe. So now I'm stuck with no mufflers on my car.

Any tips for how I can get my new cat back to fit? I have a 3" pipe on my cat and a 3" pipe on my y pipe.

FASTAZU

Is this a complete catback from Corsa? If so you may want to contact them to see if they sent the pipes. You can always take the pipes to a muffler shop and have them expand the ends so it fits.

C4ProjectCar

Yeah, it's the entire setup, part number 14115.

I plan to call Corsa tomorrow, but right now I think they're closed.

Going to a muffler shop will be my last-ditch effort if I can't make it work myself.

As a side note, I see why people install cutouts. I couldn't resist taking it for a spin without mufflers and
The drone was pretty horrible at 2500 or so though.

ch@0s

Replace the Cat with a stock replacement or have an exhaust shop fix it for you. GL

c4cruiser

I would think that when the cat got replaced, it would have been a CARB-compliant cat unless the PO bought a generic piece and did the install himself. An OEM cat should have been one that would have had the proper mounting flange. Corsa would certainly have designed their systems to fit OEM cats.

You may want to find out if the cat that is on there now will pass a visual test or at least have a CARB sticker on the car. Some shops will be sticklers about the regs and it could be some shops will not work on the car unless everything is compliant.

C4ProjectCar

Hmm, I didn't know that a CARB-compliant cat would have the flange. Mine must not be CARB-compliant then I guess. The PO definitely didn't have the ability to replace it himself, but I know he lived in Nevada and Washington for a while. Maybe he had a generic one installed there.

Right now I'm thinking about either buying the proper connector for the cat and having a shop weld it on or just having a shop weld the Corsa y-pipe to the cat. $60 for the latter, but I'm not sure I want to permanently attach it.

I wasn't aware that a shop may refuse to work on it if the cat is non-compliant. I'm thinking about taking it in tomorrow so I hope that it isn't an issue.

Thanks for the help guys.

C4ProjectCar

I've decided to have a muffler shop weld on the Y pipe. Is there anything I should pay attention to/be concerned about? Do I need to make sure that the pipe is aligned a certain way, or will the muffler shop get it right?

FASTAZU

Cool, Welding is the best way to go. If its a good shop they will line everything up. If you can see if they will let you confirm its like you want it before welding.

C4ProjectCar

Okay, I did some research and found that there are some universal cats that are CARB certified.

Before I get it welded I want to make sure that my cat is certified. Will the number be visible right on the bottom of the cat?
I looked and couldn't see anything - is it possible that the number is on the top side of the cat?

If my cat isn't certified what are the chances that a smog place will actually catch it? Do they ever check?

bogus

Magnaflow makes cats for our car, that are CARB certified.

CARB now requires an exact fitment, not based on engine size. The cats also have 2 year warranties and will also meet standard for more miles.

C4ProjectCar

The previous owner said he recently replaced the cat, so I don't want to have to replace it again, especially not after having my exhaust welded to it.

Here's a universal one from MagnaFlow that's CARB-certified. I'm wondering if I have one similar to this.
http://www.magnaflow.com/02catalytic...iversal=337005

I just don't know how to tell if mine has a CARB EO.

FASTAZU

The certified cats I have seen have a tag welded to them with brand and date along with other info. be sure to feel around it may be on the top.

C4ProjectCar

If there's the possibility of the tag being on the top then I won't sweat it. I highly doubt a smog place is going to jack up my car just to make sure I have a certified cat.

Nonetheless, I'll check myself next time I have it up on my ramps. I looked with a mirror and it's definitely not on the bottom or sides.

Thanks for the help.

WVZR-1

I believe I'd do what needed to be done to attach the Corsa as it was meant to be installed if everything from the manifold to the rear of the CAT were original.

I think anything short of that is foolish UNLESS you know the installer and have confidence that they can handle the install. I believe the ball/socket connection can be duplicated. I never needed to accomplish it but I'd certainly investigate an install that would be bolt on. I know a couple installers that I'd trust and maybe you should ask "locally" for some references, a local speed shop would likely know a shop or two that could capably handle it. A shop that can is likely going to require CARB parts to complete an install. It's their a$$ if it's done and CARB parts weren't used.

C4ProjectCar

The shop can weld a flange onto the cat, but it would cost twice as much. Besides, isn't it better to have exhaust welded than to have it clamped?

I've heard good things about this shop, and I'm confident in their work. I'll make sure it's lined up right before they weld it.

Since they aren't installing the cat, just welding onto it, I'm hoping CARB compliance won't be a problem.

I'm already going to be out near the shop, so I'm going to take it by today and see what they say.

GKK

Hey, Reid!...

Yeah, just have the muffler shop weld the flange onto the rear of the Cat or, if you need to replace the cat, the muffler shop will have the correct California compliant catalytic converter so, you don't have to search for it.

In any case, don't cut or modify any part of the Corsa Y-Pipe just to make it fit. Either have the shop weld a flange onto the end of the cat or replace the cat with the OEM part.

C4ProjectCar

Thanks Garret.

They had suggested cutting off the flange on the Y pipe to weld it to the cat.

The muffler shop quoted replacing the cat to be $250 or so and welding on a flange to be $120, whereas cutting and welding the Y pipe is only $60. Since I don't plan to remove the exhaust, budget is an issue, and I heard that welded exhaust is better, I had decided to go with the cheaper route.

However, I want to make sure I don't have it done a bad way. What are your reasons for suggesting I not have the Y pipe modified?

I called Corsa and a new Y pipe is only $120, on the off chance that I ever wanted to go back to the ball flange design.

WVZR-1

The Corsa after being cut/welded isn't probably worth half of the money you paid if you were to attempt a sale if you're unhappy. It could cost maybe three times the price of doing it right the first time vs. an attempt to short cut it the first time.

It's certainly your car and your call! Good luck!

C4ProjectCar

That was my concern too, but I've heard the exhaust in person so I doubt I'll sell it, and I know I can get a replacement Y pipe if I decide to sell it.

That being said, you've convinced me. When I go by today I'll explore the option of getting a flange welded on. I'm anxious to get it back on the road but I don't want to rush into a bad decision.

GKK

Good, decision!

Welding the Y-Pipe to the cat, will prevent the exhaust from ever being removed. Saving $60 bucks now, will end up costing more in the end when the exhaust will have to eventually be cut off and installed properly.

You never know when you'll have to remove or service the rear differential or in my case, switch the Corsa exhaust onto another C4 Vette after my 89 was totaled.

Here's a quote I always find true, "You Never have the time to do it Right but, you Always have the time to do it Twice!"...




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