De-Cat or Not??? Options

[manphibian]

Hi, i've heard mixed reviews about De-Cat pipes, some people say it caused problems, Let me know your experiences please

[Bigmeanbulldog55]

Good luck finding anything to get rid or the cat on a 94 GT. I replaced it with a header. You'll have to make a pipe if you really want a de-cat, or test-pipe set up.

[Negative]

I'm kinda either way on this so I didn't vote. I have no primary cat due to the header mod and I replaced the secondary cat with a high flow cat. No real gains from any of it except the larger pipe size and the Header flows better than the stock one. If you are not going for a full exhaust you probably shouldn't bother.
BTW - I still somehow pass emmissions for the last two years even though my two o2 sensors are 6" apart with nothing but a 2.5" pipe inbetween. I have no idea why.

Good luck finding anything to get rid or the cat on a 94 GT. I replaced it with a header. You'll have to make a pipe if you really want a de-cat, or test-pipe set up.

He could just gut the stock cat. I have a gutted one in my garage.

[manphibian]

Good luck finding anything to get rid or the cat on a 94 GT. I replaced it with a header. You'll have to make a pipe if you really want a de-cat, or test-pipe set up.

I'm in the UK so my car has the 3S-GE engine, i guess the setup is different to yours, De_cat pipes are quite common, they sell them on Ebay.

I have a stainless exhaust from the Cat back.

Just wondering if it's worth doing, if it improves response by removing restriction.... or not.

[Negative]

Not really. Our exhaust setup should be almost exactly the same though.

[kevstir]

you might have almost the same exhaust negative but you don't have anything like the 3s-ge engine on your GT's


Manphibian the decat for our cars DOES make a different, i have one on mines with a standard exhaust , it gives a bit more low down torgue that the 3s-ge lacks, makes it a well worthy mod, its the best mod iv done.

iv seen it asked on here before , the American guys always say dont do it and us UK guys say do it , i think its down to the 2.2 that the americans get already has the low down torgue where as the 3s-ge lacks it some what, also correct me if im wrong but i would think the 2.2 would run out of puff around the 6k mark where as the 3s-ge is im mid swing at the point pulling all the way to 7k, with the decat it helps you get to that 7k mark that little bit quicker but again its the low down torgue increase you feel the most.

if you get one m8 don't expect an instant gain it takes about 30 mins for the ecu to learn, i was disappointed at first but once the ecu learned i was more than happy, if you pull the ecu fuse for 10 seconds i would imagine it would learn quicker.

Kev

ps: if you dont alreday know about it there's a uk celica club

[manphibian]

thanks Kev, you'll find i've also put the same poll on CCUK
Right i think i'll go for it then.

[kevstir]

No problemo m8

you will get 90% of peeps on celica-club voting yes lol

[delusionz]

Hi all, sorry to bring up this topic again but I have a silvertop 3S-GE and when you look underneath you can see a fat attachment from the headers which I assume is the catalytic convertor, and theres another barrel after it which I assume is the resonator. I've seen straight through decat pipes for sale on the internet and I figured straight through would have the best flow and weigh alot less than the catalytic convertor but I'm told the car will sound like a tinny piece of **** if I use a straight through decat and they say to use a resonator instead. My thoughts are that other cars have a catalytic convertor and a resonator in 1 unit where as my car has them in separate units so there would not be a need to have a 2nd resonator installed in place of the cat.

So here I'm not looking for further opinions and thoughts I'm looking for people who have de-catted their 3S-GE (no fe crap) and can tell me honestly whether it sounds better or worse or the same...

[manphibian]

I actually just got round to doing this the other week...

The first part on the down pipe i still have, bit the larger section is the main cat, which i replaced with a stainless straight pipe. (the part to the left of the rusty flanges )



To fit one like mine, i had to grind away this bit of pipe that protrudes from the flange:


The difference is quite spectacular with the 3S-GE, it's like it was made to be this way! Definite increased throttle response and i estimate a few more horses too, i'm getting it dyno'd soon.

Sure, it's a little louder (ok, well a lot louder) but in no way tinny, if you get a nice thick stainless one. Although i heard the ones from Fensport.co.uk keep the sound down...

I'll make a sound clip of it later.

[delusionz]

That's awesome, sounds reassuring to me, that big round unit is the exact one I was referring to when I saw what was underneath my car, there's another smaller round barrel after the cat, is this the resonator? I know to leave this alone or it will **** with the sound.

The tinny I'm afraid of ending up with is common to the Altezza Beams. Everyone says a straight through pipe will give me a fart cannon tinny sound... Whats in your pictures is exactly what I want, why do people put extra resonators in??

[Vince-Noir]

Glad you got it done in the end there dude, i would have commented on the 'other' thread... but we know how that went unfortunately

Just how rusty were your flanges??... Looks rusty on, but quite good cleaned up separated. With mine you can actually flake rust off easily in chunks with your fingers (bolts look really bad) so im thinking if i managed to remove the cat, i'd have to have a new downpipe and cat-back system as its way too corroded to piece back together

[manphibian]

Yeah, they were pretty rusty, i had to grind the nuts off, but they were ok one they were apart, mostly just on the surface. You might be surprised once you get it off, it's pretty thick metal.

I recorded a sound clip, but came out crappy on my phone, will try tomorrow with my camera...

[Vince-Noir]

Good stuff mate, did you get the stainless fixings from Mr T or from a DIY shop?

[manphibian]

Good stuff mate, did you get the stainless fixings from Mr T or from a DIY shop?

nicked them from work mate

nut and m8 or m10 bolt - about 40-50mm long i think...

[97celiman]

import tuner magazine testing for cats and de cats and test pipes all that jazz

article about power gains they got with de-cat and putting in test pipe

the results may suprise you...

[manphibian]

My Chip is programmed to take advantage of the de-cat, so gains will be higher than that. (dyno testing this weekend)

Also like to point out, it's not illegal here to run without a cat. Only if it then fails the immissions test at the MOT is the car illegal, and cars have passed the test without the cat.

[kevstir]

that article has just measured how much top end increases the aftermarket and de cats gets, what the fail to say is if there is a bigger improvement in the low to mid range,

people always focus on the top end bhp and torque figure, why?? you hardly ever up in that rev range anyway, i would much rather have the same top end power but have a lot more grunt at the low to mid rev range.

de catting the 3s-ge is done not for all out max power but for the improvement in low and mid range torque it gives.

This post has been edited by kevstir: Jul 9, 2008 - 4:12 AM

[delusionz]

I'd be happy with 5 horse and 3 foot pounds from a $40 job since it's not a legal requirement in my country to have any at all

Perhaps that would bring back my 177hp to 173hp loss due to emissions standard in 1996

[Rusty]

ours did have a loss of HP. well mine didn't

new laws in NZ mean no exhausts over 90-95dB