Eliminating Catalytic Converter & going w/straight pipe
 

hey guys,

need yer help!

wanna take out my very "OLD" catalytic convert and switch to straight pipes... what things should i take into consideration?

since i don't have the equipment, i called a local muffler shop and they said they wouldn't do it cuz it'll mess up my computer chip. I was thinking in my head WELL can't you just do it anyway i'll pay you foo... the guy just wanted to get rid of me looks like.

What's the worst thing that could happen? gain in horse power? louder exhaust? My car's got over 140,000+ on it already and I am the third owner of it. I get enough exhaust sputting problems while accelerating, which i use redline to get rid of, but it seems that the catalytic convert or something is restricting the exhaust flow.

thanks!

:laugh2:

Consider getting a new engine if you keep straight pipes on it very long. Not a good idea! You will be seriously straining your engine with such a free flow set up. Turbo'd cars benefit from this, but N/A cars need the back pressure.

There are many others on this board with 200k+ miles on their stock cats...I have 160K+ on my stock cat, I think your sputtering problems are from other issues.

91,000 miles on stock everything =P

why don't you look into buying a high-flow cat ??

whut?
 

i drive with a straight pipe. The only strain i could feel on my engine was before i installed my short ram intake and cone filter. The engine seemed to run less harder at highway speeds. aside from the backfires on downshifting i like my setup for a daily driver. BTW i have a 175,000 miles on my car.

Replacing your cat with straight pipe will not harm your engine. You can have straight pipe coming all the way from the manifold to the exhaust tip and it will create enough backpressure for your engine, even if you go with 2 1/4" piping. You'll gain slight hp towards the end of your powerband. If you put on the RX-7 VAF, it will be noticable.

Also, it will not affect your computer. Your oxygen sensor is in your manifold, not catlytic converter.

If you went with straight pipe for your whole exhaust, it would be very loud. I have straight pipe with a muffler at the end and its still very loud. Loud enough to piss off old ppl :D

Do me a favor and tell this to my neighbor who blew all his engine seals from running 2.5 straight pipe! :rolleyes:

Some cars have multiple O2 sensors such as my Z32 which has 4 all together, 1 in each manifold and 1 before each cat. In that sense it will mess with the ECM causing the car to run much richer...hence the sulfer smell.

In regards to straight pipe not harming the engine...I think everyone would agree that any mod which causes the engine to backfire is harmful. :squint: This is my 2 cents, I'm speaking from experience...Been there done that, just don't want any other newbies to go through multiple exhaust systems like I did.

Being load doesn't make you fast, unless you drive a Honda. I kept my cat on my car cause I'm a "Rice-ist" :D

no cat. take it out. im running 2.25 all the way back and have been for about 6 months now with no issues yet. and as RX7_2ner said, there is only one O2 sensor and it's in the manifold, no sensors in or after the cat.

:eek: Holy Crap man...You and Protege Menace are post whores! :laugh: I joined the forum a month after you and look how many post I've got :crying: Can I have some of yours?

lol so the diffenition finally comes out lol:D :) (semmy-post whoring)

i haven't noticed any downgrade in low-end torque, however there was a gaping hole about an inch in front of the cat when i bought the car. what im sayin is, i don't know any other way. i've been thinkin about buying a high-flow cat too, but i always convince myself with "eh....screw it."

glass pack
 

when I had my sohc head I used no cats and straight pipe w/echo changer.but for low end and high end I had to put a glass pack where the cats were it will work trust me this added at leats 10 ponies with a cone filter.

Straight pipe
 

Mine is clogged, I'm thinkin straight pipe with the resonater?