faxshatch

Ive read that a gutted cat will not give u anymore power but i swear in my 99 hatchy it did! i mean a real noticeable differnce!? Weird, i dnt kno since the cat is in the headers do u think it would actually give it more power or am i imagining things?

99 Civic EX

makes your exhaust more free flowing, so it'll give you a little bump in power. nothing to get too excited about though.

faxshatch

yea i figured suprised me tho sounds a little louder thats all i was aimin for. but yea my mini me will give me a little bigger a jump! lol

Mr.Highlife

I did the same and noticed a bit more torque at low end..
still need to weld a pipe through it maybe even larger exhaust..

faxshatch

Yea i was just figurin cause the cat is directly off the headers it would be quite a bit better flowing.

ejprimo

if you gut the cat the diameter will be around 5". the difference between a magnaflow cat and a test pipe is about 2hp. you might lose power if you gut the cat.

faxshatch

I would gain power from the cat?? It deff seems that i gained a little but everyone knos how that works. How does that work?

QuickDxEk

Its not really about technically adding power. Its more adding response. With less restriction in your exhaust the engine doesnt work as hard, so your car is more responsive.

faxshatch

That makes since. I bet thats what it is my car has really good reponse now that i think of it.

92egSnatch

i havent really effd with my cat since i got my car how do you gut it do you have to hack it open or are there bolts holding it together this seems like a good little short term fix seeing as the exhaust has been on the car since 92 and i took off the muffler a few weeks ago and it wieghed about 50 lbs lol there was a bunch off carbon build up in there im guessing the cat is the same way this might help her breathe a little easier

mskansan

Well first if your exhaust is stock then your nuts and bolts are probably rusted together. You can try to unbolt them with the use of WD-40 or PB Blaster and good solid sockets or wrenches. Opinion 2 you can spray as I stated above and then if you have access to air tools you can hold one end with wrench (as big as you can find but the right size of the bolt or nut) then use air wrench to literally break the bolt in half and then if one half or bolt still stuck try to hammer it out. Option 3 is to use a torch and melt the bolts (experience is definitely needed here not to melt and thing else. You will have to replace the bolts of course. Also an air hammer is also handy to knock the bolt out of place if you dont want to melt the bolt completely. Now as for the cat itself, go buy a cheap pry bar straight is the best with a strike plate or the bar goes all the way through bottom of handle or if not the handle will break. This is why I say buy a cheap bar. Now the fun part you will need the biggest hammer you can find and stick the pry bar in the cat and beat the insides out ( a face mask and a friend are handy cuz of the dust and to hold the cat itself). Beat out the insides until you can see through the cat. Done

faxshatch

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mskansan &raquo;</TD></TR><TR><TD CLASS="quote">Well first if your exhaust is stock then your nuts and bolts are probably rusted together. You can try to unbolt them with the use of WD-40 or PB Blaster and good solid sockets or wrenches. Opinion 2 you can spray as I stated above and then if you have access to air tools you can hold one end with wrench (as big as you can find but the right size of the bolt or nut) then use air wrench to literally break the bolt in half and then if one half or bolt still stuck try to hammer it out. Option 3 is to use a torch and melt the bolts (experience is definitely needed here not to melt and thing else. You will have to replace the bolts of course. Also an air hammer is also handy to knock the bolt out of place if you dont want to melt the bolt completely. Now as for the cat itself, go buy a cheap pry bar straight is the best with a strike plate or the bar goes all the way through bottom of handle or if not the handle will break. This is why I say buy a cheap bar. Now the fun part you will need the biggest hammer you can find and stick the pry bar in the cat and beat the insides out ( a face mask and a friend are handy cuz of the dust and to hold the cat itself). Beat out the insides until you can see through the cat. Done </TD></TR></TABLE>

Thats how its done

Mr.Highlife

use ur jack handle & 5lb sledge

B18C5-EH2

The "gains" you guys claim from gutting the cat on any 96-00 Civic with the close coupled cat in the exhaust manifold would probably be offset by the limp mode the ECU goes into since your check engine light will be on for catalyst efficiency low and whatever else throws a code like the secondary o2 sensor, system too rich/lean codes, etc.

faxshatch

Yea i already have a bad o2 sensor car still performs well stays side by side with freind sol si 94 tho. Still good for a y7

B18C5-EH2

If someone were to dyno a car that had no check engine lights, and then gut the cat and dyno the car with the check engine codes, etc. then I'd bet money the no CEL good cat car will actually make more power.

All I can say is I'm glad you like it.

faxshatch

Thanks for the info, im gona get a new exhaust headers bask asap anyhow! Cant wait

yoffer

You do know that hollowing out your cat is iilegal right?
I highly doubt that you will actually "gain" any numbers from this mod because your losing the velocity that the cat creates.
There's not much room to improve the design of honda/acura cat's because they are pretty close to perfect, not to mention that they are quite free flowing anyway.

Mr.Highlife

i forgot to mention mine is EG chassis and ODB1

95dxsir2

i'd recommend putting a testpipe in instead of gutting the cat. get a couple feet of 2.25" exhaust pipe, cut the ends of your cat off, and weld the flanges on the 2.25" pipe. just mark the tops of the flanges so you get a plug-n-play type fit.
this will also help so you don't have an open area for exhaust to flow through like you would with a gutted cat. It's almost like having a restriction.

faxshatch

Wat thats illegal!! NO WAY

95dxsir2

Modified by 95dxsir2 at 7:49 PM 3/31/2008

2drEG

yea, its way illegal, cops will pull up to you at stop lights and stick a probe out of there window and test your emissions output, and if you are waaaay over the legal limit, you'll get a nice fine...in tennessee it's a $10,000.00 fine, i don't know about anywhere else, but i know its high around here.

blwn95civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2drEG &raquo;</TD></TR><TR><TD CLASS="quote">yea, its way illegal, cops will pull up to you at stop lights and stick a probe out of there window and test your emissions output, and if you are waaaay over the legal limit, you'll get a nice fine...in tennessee it's a $10,000.00 fine, i don't know about anywhere else, but i know its high around here. </TD></TR></TABLE>

Wow, never heard of that one... good thing i've got a turn down about mid chassis right after the shift linkage

yoffer

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by faxshatch &raquo;</TD></TR><TR><TD CLASS="quote">Wat thats illegal!! NO WAY </TD></TR></TABLE>
Like being a smart-*** now do we?
Go ahead, take your cat off and gut it, lose some horse power and get a cel, and get bad gas mileage. Im not stopping you, be a ignorant jackass.