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hey guys, i know that if you take out our cats or get a hi flow cat our CEL will come on. my friend said that he can make a resistor to bypass that CEL for the cat by sending a constant flow of volts so that the car will think it's normal. but everything else will work, say if i have another problem with the car. does anyone here have a hi flow cat or no cat and have done this and worked? also, i'm turbo'd, wut exhaust size should i run? gonna be running 7psi this year. is anyone running 3" exhaust here? thx for your help guys.

 
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i'm running 3" exhaust right now with no cat and only kick my CEL on if I push it really hard, I mean hard otherwise mine never comes on

 
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i got a 2.5inch, no cat, CEL come on now and then

 
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3" exhaust & without cat would be the best for turbocharged engine.

 
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I have 2.5" w/hi flow cat. No CEL ever. A hi flow cat WILL get that CEL off. I am going to have an interchangeable cat & straight pipe. So when I have emissions, I just switch them out.

 
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I'm throwing the TSI kit on with no cat and a 3" exhaust next weekend. Anyone have A TSI kit. They told me that something that comes with it prevents the CEL from getting triggered. Anyone running the TSI kit that would know?

 
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the tsi kit doesnt come with anything for that, i have it, if you pull your cat it will throw a cat below efficiency threshold code crap, i have a 2.5 hi flow cat laying around for my mustang and i took it and the second peice of pipe that comes with the kit and cut it and welded it in had to downsize the end pipes and then moved my factory o2 sensor back and then put my wideband in front of the cat, i ran without a cat for about a day or 2 and could'nt stand the smell, and yes you could take a resitor to the second o2 sensor output wire you would have to play with it to figure out how much resistance you will need to use, if you had a scanner it would help alot cause you could hook it up cut your 02 wire and switch out resistors until you find one that would keep it at about 1/3 the value of the first sensor and that should keep the mil off, i've noticed tho with the cat and my wideband my car runs better with the cat on it but highly recommend a aftermarket muffler, or catback atleast 2.5 inch

 
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Interesting...

I'll be sure to let my shop know. They'll figure it out. Thanks!

 
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thx for the input guys, gonna run 3" exhaust w/hi flow or no cat i guess.

 
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I'm running a 3 inch exhaust w/ no cat and an ECG O2 sim which gets rid of that CEL.

 
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like he said, nothing with the kit, only a MAP box that alters the MAP unit from seeing boost. That will keep a CEL off, that may be what they were talking about. If the MAP sees boost, thats very bad, and you will throw a code fast. So the kit does come with something to keep it off, just not the 02 sim. I would get a hi flow cat, extend the secondary 02 wires, and have a bung welded after the cat. I believe after the cat, right?

Also, have a straight pipe that can be swapped out easily. I am doing this soon as well as my friend with a 00si. So I can go with no cat, but when I have emissions or get pulled over, I can swap it out in 5 minutes and be legal. Best thing to do, IMO.

 
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I think 3" is a little to big for a 1.7L on 7psi. id only use 3" if u used a highflow cat. otherwise go 2.5" with no cat. My friends 11 second civic, used 3" piping, and i doubt u have that much power so i think 3" would hurt u more than it helps.

 
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Agreed^^