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Has anyone removed just the third cat? Stock exhaust

Started by Needmoreboost, November 01, 2013, 02:43:58 PM

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Needmoreboost

I'm looking to do this next week and wanting to make sure this is not going to increase exhaust noise by much.  I will be leaving the stock resonator in place.  So pretty much at the second cat flanges they will be running straight 2.25 pipes in replace of 3rd or 5th (actually) cat.  It looks like most of the catback and mid pipe designs remove these as well with a x type crossover.  But, most of them also remove the resonator (for more exhaust noise) which I do not want.  Anyway, for $85 bucks it seems like a reasonable mod to improve flow just a tad.  I will post some picks when completed. 
2014 Mustang GT/CS: white
Auto with custom Unleashed Tuning
Past honorable mentions: 13 SHO, 08 SRT4, 07 350Z, 03 Cobra, 03 Focus SVT, 00 GT Mustang, 91 LX Notch, etc.

TouchOfEvil

If you are going to do a x-pipe in the cats place i would remove the resonator. It's only purpose is to be an x-pipe for the system. It shouldn't make much difference in sound output.
2014 XSport

shoman04

I have Catted d-pipe, 2 1/2" x-pipe, 2 1/2 exhaust pipes and dynoMax muffles for the track. In 30min I can re-hang the stock mufflers and all you hear running are the electrical fan running with the sock mufflers on.
http://s1277.photobucket.com/user/shoman04/media/107_0004_zps5f3e7ea0.jpg.html?sort=3&o=43
2011 KONA BLU SHO,Livernois Tune,AIRAID CAI,DYNOMAX MUFFLEs,Newest member of the 12sec CLUB 12.669sec @ 107mph    2011 Ford Taurus SHO: 12.669 @ 105.050 MPH NEW FOR 2013LMS down-pipe,Magnaflow X-pipe,and Custom 2.5"exhaust pipe!! Meth and stage 5 next to be install!!!!!! METH DYNO TUNE today 405AWHP!!!WOW LMS track day 12.4209sec   :mike1:

EcoBrick Bob

Think you should do it as planned and report back.  You can always remove the resonator and install an "x-pipe" later. 

I have catted PPE downpipes, the 3rd cat delete and x-pipe instead of resonator, plus Magnaflows on back and it isn't annoying at all. Growls in town but on interstate trips like we are on now, you can hardly hear it.  NO DRONE!  Flex with the large interior area, especially over mufflers is likely noisier inside than a SHO.
2010 Red Candy/White EB Flex.. World's first 12 second Brick.. 12.904 @ 106.85 MPH - October 2011
2009 Spt. Red G8 GT - modded. best time 12.074 & 114.02 MPH
2008 White G8 GT - mods... 8.32 1/8 mi.

Naples, FL & Clear Lake, IA
Bob has decided not to post here any more, please do not PM him he will not receive it.

SHODYOU

I would about guarantee you wont hear a difference at all...

I deleted 3rd cat and replaced resonator with a 2.5" magnaflow tru-x muffler and honestly it sounded the same.
I went with an x muffler because I was worried about rasp and drone, and sometimes I wish id have went with a bare x as the car is so quiet.

Even now with catless downpipes and dynomax ultraflo's its still pretty quiet. Just a very mild growl, although its a nice tone, no raspiness and no drone.
2011 SHO - Tux Blk/blk int, 402B, acc, nav, multicontour, 20s. LMS 4X MyCal, 3bar MAP, K&N Typhoon, 170* t-stat, SP534's @ 30, Stainless Works catless DPs, Corsa catback, H&R sports, 5/16 front-7/16 rear spacer, 255/35 Hankook V12s, Lamin-X/PlastiDip

2004 Mustang GT - Comp Orange, Boss block/3.80 stroker 327", Foxlake TFS', Hellion turbo, blah blah

EcoBrick Bob

Same with mine...  At least you can hear it now!!!!
2010 Red Candy/White EB Flex.. World's first 12 second Brick.. 12.904 @ 106.85 MPH - October 2011
2009 Spt. Red G8 GT - modded. best time 12.074 & 114.02 MPH
2008 White G8 GT - mods... 8.32 1/8 mi.

Naples, FL & Clear Lake, IA
Bob has decided not to post here any more, please do not PM him he will not receive it.

Needmoreboost

Quote from: SHODYOU on November 01, 2013, 10:56:07 PM
I would about guarantee you wont hear a difference at all...

I deleted 3rd cat and replaced resonator with a 2.5" magnaflow tru-x muffler and honestly it sounded the same.
I went with an x muffler because I was worried about rasp and drone, and sometimes I wish id have went with a bare x as the car is so quiet.

Even now with catless downpipes and dynomax ultraflo's its still pretty quiet. Just a very mild growl, although its a nice tone, no raspiness and no drone.

Thanks guys.  If I dont notice at all that would be great.  ;)
2014 Mustang GT/CS: white
Auto with custom Unleashed Tuning
Past honorable mentions: 13 SHO, 08 SRT4, 07 350Z, 03 Cobra, 03 Focus SVT, 00 GT Mustang, 91 LX Notch, etc.

Excalibur

No pics? Are you able to eliminate the cel you would get doing this with the unleashed tune, or are defoulers a must?
2013 PP SHO; k&n drop-in, 3bar, unleashed tune.

AJP turbo

Defoulers wont help anything...removing the third cat has no effect on anything since its after the all the o2 sensors...3rd cat is for the planet
SCT Dealer/Custom Calibrator                        
Specializing in 3.5 Ecoboost   
Remote/email custom tuning including E85 blends 
Authorized retailer for all SCT devices. 
 
Former:2014 PP SHO
3 bar 93 tune, Airaid, Stainless Works non catted DP's  
405whp/520tq
Dyno
     
Current:2016 F150 2.7 Ecoboost
Tuning in progress

TooFast4SHO

I have the PPE Catted DP's and deleted the resonator and 3rd cat with stock mufflers, it is still REALLY quiet driving around, kinda bumms me out a little.
2014 SHO non PP, Livernois 3bar v8 tune, PPE Catted Downpipes, 3rd cat delete with straight pipe stock back, H&R Dropped Springs, Low Temp Thermo. Adaptive Cruise, Collision Avoidance, Lane Keeping, Auto Brights..

12.99 @ 106.4 with 3/4 tank of gas and spare etc. in car.