Catless down pipes - Why?

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Apr 30, 2023 | 08:35 AM

#21

^&right

Drifting

Joined: Mar 2022

Posts: 1,378

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From: Indiana

Catless headers and X pipe here. I will say when I picked it up after install and dyno tune is was obnoxiously loud. Love hate thing. But I have NPP and tuner had it set on track exhaust for effect. Set in stealth mode it is a tad bit louder than stock, but barely. Nice muted growl. Track mode sounds near NASCAR levels. I click that when a Mustang pulls up and revs its engine. Usually makes them do the turn of shame.

I gained 40 HP/TQ, also did CAI at the time. I had a deal on 2" headers so that's what I used. 1 7/8" might have gotten me another 5-10 HP, maybe. Having NPP I love it. Without NPP I would not be happy. NASCAR loud gets old fast.

Downside. With no cats its like driving my high school Mustang with a built 302 and glasspacks. Exhaust fumes. There are times the fumes linger in the garage for a time. Putting around town in slow traffic my wife says I come home smelling like gas. I notice that occassionaly. There have been times I thought of getting a catted X pipe to help with that. No issues with burnt wires. My tuner does a good job. Never noticed any heat issues of any kind.

Apr 30, 2023 | 09:54 AM

#22

Factoid

Race Director

Joined: Jul 2018

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From: San Antonio, TX/Mahopac, NY

2024 Corvette of the Year Finalist - Modified

2024 Corvette of the Year Finalist - Unmodified

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I’m surprised no one talked about the smell until now.

In my opinion, headers and high flow cats are the best way to go for both power and lower emissions/smell.

Apr 30, 2023 | 07:56 PM

#23

^&right

Drifting

Joined: Mar 2022

Posts: 1,378

Likes: 793

From: Indiana

I've thought of trying to fit some high flow cats into the X pipe. I have a 3" Texas Speed set up. If anyone knows of a direct fit solution to get cats in there, I'd be happy to hear it

May 12, 2023 | 12:41 PM

#24

oaklawn

Cruising

Joined: Jun 2022

Posts: 10

Likes: 1

Quote:

Originally Posted by 6Speeder

I put on the catless down pipes on my 15 M7 Z06, with before and after dynos, same dyno, similar conditions, different dates. The car gained 20+ SAE RWHP, maybe the same RWTQ, and got stupid loud with the stock mufflers open. I like it, but it does set off car alarms and some complain.

So all you did is add catless pipes and kept the stock mufflers? No, headers? I'm curious because I have a 2018 C7 stock stingray. I'm looking to getting it a little louder, but I've been told that just changing to a catless x-pipe won't make a difference and that I should also add Borla/Corsa mufflers. My other issue is trying to find a place that sells the catless x-pipe. What are your thoughts?

May 12, 2023 | 01:43 PM

#25

9sec

Safety Car

Joined: Jul 2019

Posts: 3,827

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From: nashville TN

Quote:

Originally Posted by oaklawn

I added tge eos catless mid pipe and the car is noticeably louder especially at cold start it barks loud! I have tge eos Downpipes as well but haven’t installed them yet. Tge oem setup is headers like a hooker shorty Downpipes and mid pipes with axle back mufflers. I did a diy mild to wild so I can keep it quiet leaving my subdivision at nite

May 12, 2023 | 01:54 PM

#26

Dcasole

Le Mans Master

Joined: Oct 2014

Posts: 8,672

Likes: 2,726

From: Atlanta GA

I agree with 9 Sec , whoever told that adding a catless x pipe does not make it louder might be mistaken , back when my car was stock I added the x pipe and as stated above it was a lot louder than stock especially when you were into the throttle
I to use a mild to wild switch that is slaved to my home link buttons on my visor because i now have headers and I dont want my neighbors complaining about how loud it is on Cold Start 🤣

Dave

May 13, 2023 | 08:24 AM

#27

6Speeder

Safety Car

Joined: May 2000

Posts: 4,819

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From: Albuquerque NM

Quote:

Originally Posted by oaklawn

I gutted the stock X pipe, and replaced the down pipes, eliminating the main cats. The manifolds, mufflers, and the rest of the exhaust system is stock. The first thing I did was gut the secondary cats and there was very little change in volume or seat of the pants power (I didn't expect any). Eliminating the main cats greatly increased the sound and as I said, added 20 SAE RWHP. You will need a tune to turn off the CEL or fool the secondary O2 sensors. I then tuned it for E-85 and REALLY picked up some power. This is on an LT4. The same changes on an LT1 probably won't increase power as much. Sound? I don't know.