Hey all-

Bought an 03 V-8 4-Runner and am thinking about pulling the cats and running straight pipes out the back...I can get em around the spare tire no prob. The vehicle is so damn quiet that I can barely even tell it is running at times. Guess that's what I get for becoming accustomed to my highly tuned Lightning that roared like a S.O.B. Anyway, just curious about all your thoughts on this...I'm not worried about emmisions as I live in Washington State, and assume that the Runner would still be fairly quiet with the cats removed anyway as the motor is so fine tuned...just looking to pick up some extra HP (30+ is my guess with the cats gone) before I supercharge it in the fall. Any input would be much appreciated. Thanks.

Anthony

 

arent there laws in states that say you have to leave your cat on? i know here in ga, you can take off the muffler, but you have to leave the cat on.

 

I was thinking of doing the same thing, but since I live in NY I would have to swap them back on when inspection time comes but thats no big deal, I might even get the Borla dual exhaust, their suppost to be the best when it comes to true dual.

At 1st I thought the engine/exhaust was quiet but now with just oer 4000 miles the sound is starting to pick up, in fact I was on the highway today just flooring it to hear the engine roar, take it from me it sound slightly different from when it was at 1000 miles, sounds like it has more bass now

Keep us updated on the SC cause I might go that route

 

I dont want to come off as an envirofreak, but after taking my environmental engineering class I realize the importance of clean air and etc. The Cat is there for a reason and serves a specific purpose. I'd only support removing the cat for specific limited use (racing or other instances of need). I know a few cars with removed cats aren't going to make too much of a difference, but still we all can do what we can. So if you feel the need for your cat to be removed for your daily trip to work or the grocery store then that is your choice.

http://auto.howstuffworks.com/catalytic-converter.htm

 

i agree with Nolan

 

i live in wa too, i'd recommend getting a hi-flow cat or something of that sort, and a cherry bomb muffler behind it

don't give all those enviro-freaks any more reasons to mess with our state...

 

Thanks for all the responses.

I was talking to a friend of mine about going the high flow performance-cat route as well, and that is probably the more realistic solution. Just wanted to get some feedback from you guys. Thanks for the help. BTW, anyone have any idea on the HP/TQ gains with a better catalitic, muffler and exhaust on the 4.7 liter V-8??

Anthony

 

Removing working cat(s) is a federal offense.

 

I would consider REPLACING the cats with a cat that is better... To try and remove that damn smell.

I wouldn't drive around w/o cat's on the car.

 

Aside from the the obvious environment issues. There are perfromance issues with taking off the cat.
Your O2 sensor is before the cat on vehicles and it reads the back pressure from the cat to give a proper reading so the vehicle runs right.
If you remove the cat, the O2 sensor will be reading wrong and that will make your truck run wrong. Too lean or too rich. This will negate your gains from removing it. you will have to update your ECU. This is something you will prolly have to do when you get a high flow cat anyway.

just my .02

 

I remember hearing somewhere that you could leak carbon monoxide into your cab if you take those out?


Well, regardless... I'm with the other guys. Don't drive without them.

 

How many times are we going to debate this topic? Can we just have a sticky topic to discuss this issue? It come up like once a week.

Thanks,
John

 

So are we also going to put a sticky on the other 500 topics that come each week, all the same?

 

Please do. It feels that alot of the same questions are asked. This causes the other posts to move down to quick and get unread.

Thanks,
John