Exhaust confusion

[MattyB777]

hey guys,

ok, so i am going to put a full exhaust system on my 90 stanza next week (from the manifold back).

Ive researched alll day today about the catalytic converters. i have a new cat i am going to put on and i am seriousely considering gutting the cat (its just a small "white box" cat from a local autoparts store).

Now im getting pissed because all im finding are dumbasses that say that gutting the cat will "restrict airflow," HOW IN THE FREAKIN HELL WILL IT RESTRICT AIRFLOW! or finding other people who think there so funny and say to get a knife and slice your pet cat open.

Sorry for ranting, i feel better now.  anyway, my stanza has a stock KA24E, FWD, 5-spd (stock clutch for now) and i want to put a 2.25 inch exhaust on it from the manifold back with a 2.25 inch in and out thrush glasspack muffler.

All im trying to find out is if i gut the cat will my vehicle run better than leaving it alone? also will the KA sound "tinny"? and i also read that the KA needs the backpressure from the cat, does it really?

 im so confused can you please help me out?


Thank you,

Matt

[chr1S]

lol there must be something in the water for some of you americans.

gutting the cat is illegal and not worth it, you will not pass your "SMOG" test or whatever you guys use. Let alone cop a fine if you get caught with a gutted cat.

Save your energy, time and money, just use the one you have and be done with it, you won't notice a thing apart from a louder exhaust.

Also - gutting it does not make it restrictive, as you said. Running a cat does, BUT a high flow unit is fine for our applications.. hell a normal one is LOL.

[MattyB777]

Yeah some of us amerikans are semi retarted. haha

yes gutting the cat is illegal, however, for the emissions test where i live, 1996 and newer vehicles get a visual check to make sure everything is there, a gascap pressure test, and the vehicle gets plugged into a computer to make sure the vehicle is running like it should.

Now, for 1995 and older vehicles, there is just a gascap pressure test and a visual check. noone looks inside the cat to see if it was gutted.

I no you said not to do it, but if i were to will it be ALOT louder if it is gutted? also does the KA like the backpressure the cat would provide? the last thing i need to know is, is a 2.25 inch exhaust good enough or should i go to the 2.50 inch right away?

Thank you,


Matt

[SSS]

Go for 2.5", all with mandrel bends. If you consider running a gutted cat, put a pipe right through that is the same diameter as the rest of your exhaust.

[Colby]

And for the record engines requiring exhaust backpressure is a myth.  It will change your efficiency but as far as power is concerned, generally, the less exhaust pressure the better.

Check out this article for handy tips about exhaust.
http://www.autospeed.com/cms/A_0877/article.html

[MattyB777]

just a little update,

i finally got my exhaust put on my car. its loud and i love it.

i took your advice and did not gut the cat.

the exhaust is 2.5 inches from the manifold to the rear, with a cheap cat, and a large glasspack right under the rear bumper.

in case anyone would lke to know, i got it installed in Allentown, PA at a small shop called Aluminodi Customs, they did a great job, very professional, and the price was amazing ($220)

I would like to thank all of you for your help.

Thanks Again!

Matt

[Colby]

man $220 is soo cheap!
No way you would get it done for that here in Aus!!!
Good work.

[MattyB777]

yeah i no, i was expecting to pay double that for the full exhaust from the manifold back with the exhaust pipes at 2.5 inches. i am so thrilled with it.

I love my stanza!