Effect of cat delete - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Stormalong · 06-09-2014, 09:18 PM

Hey guys, I'm new to this stuff, so forgive the noob question.

What would be the sound and performance effects of a cat delete on the stock exhaust? (I already know it will make you fail the emissions test).

I'm curious if anyone actually knows the answer to this, because it seems like something people never do (ie if they do a cat delete they also change other things at the same time, so you can't isolate the effects of just the cat delete).

Tye300 · 06-09-2014, 09:26 PM

Are you keeping the stock header? If you are, you will just gain some volume in your exhaust note. If you will be swapping a catless header, your exhaust note will be raspy.

edeekeos · 06-10-2014, 03:19 AM

Not sure about performance gains/losses, but here are a couple sound clips comparing 100% stock vs resonated cat delete.

[ame]http://youtu.be/ytvCLr-XM2U[/ame]
[ame]http://youtu.be/SF8uvoWga7E[/ame]

cdrazic93 · 06-10-2014, 03:22 AM

Performance wise, yes there will be an increase over stock. That said, the difference between a cat delete pipe and a HFC pipe is like 1 hp, but with the addition of being able to pass emissions, and less rasp.

cpnslow · 06-10-2014, 03:26 AM

Funny, as I was about to ask the same thing. I'm getting a Milltek exhaust system installed on Friday, and am trying to decide on the primary catback (secondary cat delete) or the secondary catback (no cat delete), and if I'd notice any difference between the two in sound or performance (with no tuning). Any recommendations?

h4nh · 06-10-2014, 04:06 AM

Quote:

Originally Posted by cpnslow

Funny, as I was about to ask the same thing. I'm getting a Milltek exhaust system installed on Friday, and am trying to decide on the primary catback (secondary cat delete) or the secondary catback (no cat delete), and if I'd notice any difference between the two in sound or performance (with no tuning). Any recommendations?

Yes it'll be noticeably louder/ faster. Factory cats are restrictive. High flow cats would be good alternative if you wanna keep emissions.

s2d4 · 06-10-2014, 05:13 AM

Until someone has passed emissions, it's all speculations at this point.

There is no rasp if your remove header only, otherwise if you have the right CBE, no rasp either. Not much performance wise after replacing headers unless FI.

People make the mistake of doing back to front, should definitely attempt from header back in terms of sounds and performance.

CruiseZen · 06-10-2014, 09:06 AM

Quote:

Originally Posted by cdrazic93

Performance wise, yes there will be an increase over stock. That said, the difference between a cat delete pipe and a HFC pipe is like 1 hp, but with the addition of being able to pass emissions, and less rasp.

Is it really possible to pass emissions testing with a HFC? I've yet to see a post on this board where someone says they have. Is there anyone out there who can speak from direct experience? My gut feeling is that any changes to the header or cat will likely lead to failing the emissions test, but what do I know, I only stayed in a Holiday Inn Express a couple of weeks ago.

ecko04 · 06-10-2014, 09:28 AM

Quote:

Originally Posted by CruiseZen

Is it really possible to pass emissions testing with a HFC? I've yet to see a post on this board where someone says they have. Is there anyone out there who can speak from direct experience? My gut feeling is that any changes to the header or cat will likely lead to failing the emissions test, but what do I know, I only stayed in a Holiday Inn Express a couple of weeks ago.

There's no blanket statement for passing emission testing. Each state is different. In the states that my car is registered (VA, AL, GA) I know what the requirements are to keep my vehicles street legal, all the way down to the tint requirement.

With that being said, a cat is a cat, in those states, whether it's built into the header or is a HFC. In California that previous statement isn't true. In the states I listed only 1 cat is required, not 2 so a free flowing header can be added and a front pipe that incorporates an HFC.

In regards to emission/smog testing you'd be better off knowing the laws for your state and county. For example, only in GA only vehicles registered in the counties adjacent to and within the city limits of Atlanta have emission testing, all the others do not.

Some states require a visual test, some only require an OBDII readiness check...it's best to know your own laws than rely on a blanket statement on a forum.

s2d4 · 06-10-2014, 10:46 AM

There is no cat in the midpipe.

BOND007_LTK · 08-16-2018, 12:28 AM

Quote:

Originally Posted by s2d4

There is no cat in the midpipe.

But one in the front pipe apparently. Plus 1 in the header.

FirstWinter · 08-16-2018, 12:41 AM

@BOND007_LTK

FRSBRZGT86FAN · 08-16-2018, 01:05 AM

Quote:

Originally Posted by BOND007_LTK

But one in the front pipe apparently. Plus 1 in the header.

Quote:

Originally Posted by FirstWinter

@BOND007_LTK

Yea holy shit

how the hell you manage to necro a thread from 4 years ago with a response like that

06-09-2014, 09:26 PM	#2
Tye300 Senior Member Join Date: Oct 2012 Drives: Toyota 86 TRD Version AT Location: Manila, Philippines Posts: 883 Thanks: 548 Thanked 599 Times in 283 Posts Mentioned: 20 Post(s) Tagged: 1 Thread(s)	Are you keeping the stock header? If you are, you will just gain some volume in your exhaust note. If you will be swapping a catless header, your exhaust note will be raspy. __________________ Vortech Supercharged Flex Fuel 86 TRD AT Visit my build thread here.

06-10-2014, 03:22 AM	#4
cdrazic93 Junior Join Date: Aug 2013 Drives: a car Location: Probably at school Posts: 4,341 Thanks: 3,184 Thanked 2,512 Times in 1,502 Posts Mentioned: 20 Post(s) Tagged: 0 Thread(s)	Performance wise, yes there will be an increase over stock. That said, the difference between a cat delete pipe and a HFC pipe is like 1 hp, but with the addition of being able to pass emissions, and less rasp. __________________ "Ah! What music! They could have never imagined, those pioneers who invented the automobile, that it would posses us like this, our imaginations, our dreams. Men love women, but even more than that, men love CARS!"-Lord Hesketh

06-10-2014, 05:13 AM	#7
s2d4 Senior Member Join Date: Mar 2013 Drives: R32 GTR, AW11 MR2 SC, GTS86 R Location: OZ Posts: 2,615 Thanks: 603 Thanked 1,223 Times in 708 Posts Mentioned: 35 Post(s) Tagged: 0 Thread(s)	Until someone has passed emissions, it's all speculations at this point. There is no rasp if your remove header only, otherwise if you have the right CBE, no rasp either. Not much performance wise after replacing headers unless FI. People make the mistake of doing back to front, should definitely attempt from header back in terms of sounds and performance. __________________

06-10-2014, 10:46 AM	#10
s2d4 Senior Member Join Date: Mar 2013 Drives: R32 GTR, AW11 MR2 SC, GTS86 R Location: OZ Posts: 2,615 Thanks: 603 Thanked 1,223 Times in 708 Posts Mentioned: 35 Post(s) Tagged: 0 Thread(s)	There is no cat in the midpipe. __________________

08-16-2018, 12:41 AM	#12
FirstWinter Senior Member Join Date: Nov 2015 Drives: Car Location: Location Posts: 646 Thanks: 374 Thanked 422 Times in 254 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	@BOND007_LTK Attached Images

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