No cats - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

tzbang · 11-29-2015, 09:44 PM

So far I've put on a catless Gruppe-S header & overpipe. I've got the quiet rumble now and would like to liven it up a bit more.

I don't have to have a cat where I live. Should I ditch the second cat for a straight pipe with the stock rear muffler? Or would I be better to replace the rear muffler as well?

Basically I'm wondering if the next restriction to replace after the header & over-pipe is the second cat or the OEM muffler?

VirginiaBRZ · 11-29-2015, 09:50 PM

Quote:

Originally Posted by tzbang

So far I've put on a catless Gruppe-S header & overpipe. I've got the quiet rumble now and would like to liven it up a bit more.

I don't have to have a cat where I live. Should I ditch the second cat for a straight pipe with the stock rear muffler? Or would I be better to replace the rear muffler as well?

Basically I'm wondering if the next restriction to replace after the header & over-pipe is the second cat or the OEM muffler?

Correct me if im wrong (someone else) but replacing the OEM catback would probably liven it up way more than making your front pipe catless.

Edit: actually im 100% sure replacing OEM catback would make liven it up more...

churchx · 11-29-2015, 10:46 PM

2nd cat doesn't impact exhaust that much as one in header (which you removed by getting catless header), which was the main performance killer. I wouldn't expect much from changing frontpipe's cat to high flow one and i wouldn't want to eliminate altogether unless it's race only car not used daily thus not having to deal with MOT inspections and alike. You may get some on top of catless header gains, but it will be minimal. What you'll get certainly in fully catless exhaust - it will be much louder.

adamg · 11-29-2015, 10:47 PM

catless front pipe will add a little more sound and little more power. catback will give you the biggest difference in sound. really depends how loud you want to go

tzbang · 11-30-2015, 03:27 PM

I don't want to go too loud, just want a nice rumble and to be able to hear it when I put my foot down. I suppose if the second cat isn't much of a restriction and makes it too loud without it, maybe I should just leave it..

Perhaps I'll just get a 2.5 cat-back and see what it's like and I can always cut out the second cat later.

Luftwaffel · 11-30-2015, 03:48 PM

It all depends what you go with, man. N1 style with single cat is louder than my full catless Perrin. By a quite a lot. I would imagine the stock CBE might get raspy if you delete both cats, too, but I can't confirm.

fang_gt86 · 11-30-2015, 03:59 PM

Whatever you do don't make it sound like this guy's..

[ame="https://www.youtube.com/watch?v=EwdEQ-9_gHo"]Scion Fr-s Borla UEL header w/Straight pipe (THIS - YouTube[/ame]

WhiteFRS69 · 11-30-2015, 04:07 PM

Quote:

Originally Posted by fang_gt86

Whatever you do don't make it sound like this guy's..

sounds great IMO.... for a race car

tzbang · 11-30-2015, 04:37 PM

well since I'm in NZ I've got cheaper access to X-Force products than US ones. I guess most of you have probably never hear of them?
http://www.xforce.com.au/bolt-on-sys...0/vid-99002065

I've been told 100CPSI cat won't make much of a difference over the OEM one. So for me it would either be no cat at all or leave OEM cat there with a cat-back 2.5 system.

11-29-2015, 09:44 PM	#1
tzbang Senior Member Join Date: Oct 2014 Drives: 2013 GT86 Location: New Zealand Posts: 109 Thanks: 3 Thanked 8 Times in 7 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	No cats So far I've put on a catless Gruppe-S header & overpipe. I've got the quiet rumble now and would like to liven it up a bit more. I don't have to have a cat where I live. Should I ditch the second cat for a straight pipe with the stock rear muffler? Or would I be better to replace the rear muffler as well? Basically I'm wondering if the next restriction to replace after the header & over-pipe is the second cat or the OEM muffler?

11-30-2015, 03:59 PM	#7
fang_gt86 FR Noob Join Date: Jun 2013 Drives: FR-S Location: DFW Posts: 792 Thanks: 218 Thanked 614 Times in 318 Posts Mentioned: 2 Post(s) Tagged: 3 Thread(s)	Whatever you do don't make it sound like this guy's.. [ame="https://www.youtube.com/watch?v=EwdEQ-9_gHo"]Scion Fr-s Borla UEL header w/Straight pipe (THIS - YouTube[/ame] __________________ "I'm having too much fun to care about horsepower" - Unknown 6MT FR-S Whiteout:OFT- OTS V2 Stage 2 (93oct & E85), Tomei UEL, Invidia OP, JDL UltraQuiet FP, Ark Grip catback, GS hood struts, Perrin Inlet & K&N drop-in

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11-29-2015, 10:46 PM	#3
churchx Senior Member Join Date: Mar 2015 Drives: 2014 GT86 Location: Latvia, Riga Posts: 4,333 Thanks: 696 Thanked 2,085 Times in 1,436 Posts Mentioned: 53 Post(s) Tagged: 1 Thread(s)	2nd cat doesn't impact exhaust that much as one in header (which you removed by getting catless header), which was the main performance killer. I wouldn't expect much from changing frontpipe's cat to high flow one and i wouldn't want to eliminate altogether unless it's race only car not used daily thus not having to deal with MOT inspections and alike. You may get some on top of catless header gains, but it will be minimal. What you'll get certainly in fully catless exhaust - it will be much louder.

11-29-2015, 10:47 PM	#4
adamg Senior Member Join Date: Nov 2014 Drives: brz Location: United States Posts: 780 Thanks: 194 Thanked 405 Times in 212 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	catless front pipe will add a little more sound and little more power. catback will give you the biggest difference in sound. really depends how loud you want to go

11-30-2015, 03:27 PM	#5
tzbang Senior Member Join Date: Oct 2014 Drives: 2013 GT86 Location: New Zealand Posts: 109 Thanks: 3 Thanked 8 Times in 7 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	I don't want to go too loud, just want a nice rumble and to be able to hear it when I put my foot down. I suppose if the second cat isn't much of a restriction and makes it too loud without it, maybe I should just leave it.. Perhaps I'll just get a 2.5 cat-back and see what it's like and I can always cut out the second cat later.

11-30-2015, 04:37 PM	#9
tzbang Senior Member Join Date: Oct 2014 Drives: 2013 GT86 Location: New Zealand Posts: 109 Thanks: 3 Thanked 8 Times in 7 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	well since I'm in NZ I've got cheaper access to X-Force products than US ones. I guess most of you have probably never hear of them? http://www.xforce.com.au/bolt-on-sys...0/vid-99002065 I've been told 100CPSI cat won't make much of a difference over the OEM one. So for me it would either be no cat at all or leave OEM cat there with a cat-back 2.5 system.

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