i am thinking of removing my cat to free things up a bit. my only concern is that dang check engine light will for sure come on. what is the best way to make sure that dont happen?

 

Buy a check engine light eliminator. I'm planning on getting weapon-r's CEL for my project when I need it

 

Not worth it, modern cats on an otherwise stock motor do not rob horsepower. Just leave it alone.

 

Yeah I did one on mine and I can't tell a bit of difference. Except now the exhaust stinks a little. But yes u can make it so the light won't come on.

 

the L15a loses mid range torque by removing the cat, so I wouldnt recomment removing it.

that being said using a mechanical o2 eliminator bung will solve the problem or running a flashpro and making sure the ecu isnt using the secondary o2 sensor.

 

And yes, you will be able to pass emissions without the catalytic converter, assuming they don't do a visual inspection. Even still, depending on which pipe you get it may have a bulge which "looks" like the catalytic converter and may fool the inspector. Do as others have suggested and invest $5USD in a Check Engine Light eliminator. Basically it is a metal pipe that extends the O2 sensor farther away from the downpipe to allow it to read less exhaust and fools the ECU into thinking that everything is okay. It also gets rid of the Check Engine Light on your instrument cluster. When it comes time for emissions choose the line with the OBD2 sensor inspection, NOT the sniffer one. If you go to the sniffer line you will fail because no catalytic converter = more exhaust = you fail emissions. They hook up the OBD2 sensor and see that everything is "okay" and send you on your way. Worst case scenario, keep your stock pipe so you can swap it back in in case you fail emissions the first time.

 

If you are in CA you will definitely fail emissions to anyone in CA reading this thread don't get any ideas

 

i am not in california or in any state that does emissions tests. i just want better gas mileage and i think that taking my cat off would only help.

 

No, it won't do anything much except make your exhaust smell more like rotten eggs from the NoX. Unless your cat honeycomb is broken into pieces and rattling around, removing it won't help at all.

Narrower, lighter tires and wheels and aero improvements will do a ton more for you.

 

first of all, removing the cat won't help a bit because factory exhausts are carefully tested to produce good exhaust flow and low emissions to match combustion requirements. Opening the exhaust will just make it louder and likely decrease mpg. Thebest systems sre exhaust systems after the cat. There you can get useful power increases though sometimes they also will reduce mpg too.
Open exhausts need new cams, valves, and often gearu=ing to be efficient.
Yes, likely the check engine light will come on and there is no way to avoid it except to rewrite the program.

 

its not the state, its the feds that you run afoul of; emission laws are federal laws and any attempt to break one or more of them is subject to prosecution.
Now that you have published your intent I recommend you do not remove the cataytic exhaust. You never know who is listening. Besides you are likely to get more from cat-back exhausts.
i can attest to that. Many years ago I ran an article on rejetting a BMW 2002 for better power delivery. Fed Agents dropped by my office to 'gently' remind me I couldn't legally do that. Nowdays there's no gentle reminders.

 

What are you getting for mileage now, and in what conditions? What have you already done to increase mileage, and what other mods are you considering?

 

You won't see anything good from just removing the cat. If you're going to do a full exhaust (H,DP, E) then it's a different story. Also at that point you wanna think about a Hondata FP. Well worth the upgrade even stock.