Jump to content
SAU Community

R34 Gt-t Cat Replacement Pipe

R34_Wong

By R34_Wong,
in Engines & Forced Induction

 Share

Recommended Posts

R34_Wong Mentor

R34_Wong

Posted
Posted

Hi everyone,

I was wondering what would be the effects of removing the standard cat and replacing it with a 3" stainless steel on a one would be on a near GT-T?

I've heard that this may result to a huge loss in lower end power.

Can anyone advise? Thanks in advance!

Link to comment
https://www.sau.com.au/forums/topic/214771-r34-gt-t-cat-replacement-pipe/
Share on other sites
R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Whoever told you you'll loose power/top end is a moron :D

If the car is stock, probably no real increase as the rest of the exhaust needs to be upgraded.

Apart from the fact its illegal, and it will cause your car to get a lot of build up on the rear bar (in less than a week if daily driven)... you wont loose power or anything. Its the non-legal hi-flow cat basically

R34_Wong Mentor

R34_Wong

Posted
  • Author
Posted
Whoever told you you'll loose power/top end is a moron :D

If the car is stock, probably no real increase as the rest of the exhaust needs to be upgraded.

Apart from the fact its illegal, and it will cause your car to get a lot of build up on the rear bar (in less than a week if daily driven)... you wont loose power or anything. Its the non-legal hi-flow cat basically

Well the exhaust system is turbo back stainless steel. I've noticed it's a lot smoother to drive now (is that odd?), but I dunno if its me, I feel as if theres a loss of power lower end (do excuse my error). The build up will be an issue I guess... but I've got a black car so maybe not as noticable... (more whipping every day?)

R34NRG Grand Master

R34NRG

Posted
Posted (edited)

why on earth would u replace just the cat? thats just stupid? your doing a half ass job, why not do the whole exhaust.

if it is a turbo back exhaust the only reason that i can think of as to why it might feel not as powerful is the power is alot smoother in delivery rather then a light switch on/off situation.

for example\

by 3,00rpm you might be makn only 80kw with the standard cat and only 60kw with the bigger cat.

but at 4,000rpm your makn 90kw but with the bigger cat your at 120kw.

but basicly who ever told u your losing power by gettn a bigger exhaust is a MORON

im very very very sure you got more power, it justs just proberly bringing the power on smoother.......

best way to find out is dyno it

Edited by R34NRG
Scottydoo Community Regular

Scottydoo

Posted
Posted

You should just get one of the Catco 3" cat's with the 5" body,they flow not too much less than a de-cat pipe anyway really and they r legal and your exhaust wont stink... you can get them off this forum i think the guys user name is Batmbl or something like that, I have one on my car (with a 3" turbo back exhaust) and its making more power everywhere

R34_Wong Mentor

R34_Wong

Posted
  • Author
Posted
You should just get one of the Catco 3" cat's with the 5" body,they flow not too much less than a de-cat pipe anyway really and they r legal and your exhaust wont stink... you can get them off this forum i think the guys user name is Batmbl or something like that, I have one on my car (with a 3" turbo back exhaust) and its making more power everywhere

Thanks guys, been a great help. I was thinking that I didn't feel a large loss for lower end power. Definately have a smoother ride. Need to get some cash up I think. Anyway, once again thanks for all the help.

limpus Mentor

limpus

Posted
Posted
why on earth would u replace just the cat? thats just stupid? your doing a half ass job, why not do the whole exhaust.

if it is a turbo back exhaust the only reason that i can think of as to why it might feel not as powerful is the power is alot smoother in delivery rather then a light switch on/off situation.

for example\

by 3,00rpm you might be makn only 80kw with the standard cat and only 60kw with the bigger cat.

but at 4,000rpm your makn 90kw but with the bigger cat your at 120kw.

but basicly who ever told u your losing power by gettn a bigger exhaust is a MORON

im very very very sure you got more power, it justs just proberly bringing the power on smoother.......

best way to find out is dyno it

Read the post above and you will see he already has an aftermarket exhaust...

R34_Wong Mentor

R34_Wong

Posted
  • Author
Posted
Read the post above and you will see he already has an aftermarket exhaust...

Indeed your right. I was driving the car today and it really does feel like its lost a lot of lower end power. Theres definately a smoother ride, moving through the gears, the car doesn't thrash as violently as I remember it being and when boost kicks in, its definately not what it used to be (maybe I'm getting used to it?). Would this actually be the case or am I being too obsessive? I had a look at the cat I removed and from what I can tell, it may have actually been a hi flow cat (looks a lot larger anyway, bugger!). What would everyones thoughts be?

some_cs_student Veteran

some_cs_student

Posted
Posted

Just be warned that in some states having a de-cat pipe can be a huge fine. Victoria is somewhere around 10K if the EPA catches you...

Batmbl sells quality metal cats, although I'd recommend the extra $$$ to get one with flanges from him, as I found getting someone to fit flanges carefully was expensive ;)

R34_Wong Mentor

R34_Wong

Posted
  • Author
Posted
Just be warned that in some states having a de-cat pipe can be a huge fine. Victoria is somewhere around 10K if the EPA catches you...

Batmbl sells quality metal cats, although I'd recommend the extra $$ to get one with flanges from him, as I found getting someone to fit flanges carefully was expensive ;)

Damn! Thanks for the heads up. Thats a scary thought to have looming above me... I'll be sure to do some checking out soon~

r33cruiser Grand Master

r33cruiser

Posted
Posted (edited)
10K if the EPA catches you

here in qld only the COMPANY that installed it gets that fine. e.g an exhaust shop.

if u are caught u are defected and off to court u go.

keep it in the garage for the track mate. u can smell a decat'd exhaust a mile away.

Edited by r33cruiser
R34_Wong Mentor

R34_Wong

Posted
  • Author
Posted
here in qld only the COMPANY that installed it gets that fine. e.g an exhaust shop.

if u are caught u are defected and off to court u go.

keep it in the garage for the track mate. u can smell a decat'd exhaust a mile away.

I agree with you there. Looks like more than likely I'll get myself a high flow cat and replace the pipe. A shame... I'll miss that roar. Thanks for the genuine advice once again, its good to hear the pros and cons from everyone

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • sunsetR33
      Unpeeling the Orange

      By sunsetR33 · Posted

      Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • Kapr
      What brakes on R34 GTT(Europe)

      By Kapr · Posted

      No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • wizlb
      Who has a Infiniti Q60, Q50 (V37)?

      By wizlb · Posted

      I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Kinkstaah
      Starting again

      By Kinkstaah · Posted

      Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
    • GTSBoy
      What brakes on R34 GTT(Europe)

      By GTSBoy · Posted

      I'm not going to recommend an EBC pad. I don't like them. Just about anything else would suit me better. I've been using Intima pads for a while now.
×
×
  • Create New...