adamant186

Hello everyone. I was wondering if removing the cat is bad on a 2011 gts? I know it is less than legal to say the least but will it harm my motor/ throw codes?? Any info would be great. ( I already have an injen cai, and a greddy se axel back.)

lancer0220

iTrader: (6)

leave the cat

SamsonEvoX

I would leave the cat. It serves the purpose of keeping emissions down. On a stock car, there is little to be gained in hp and then you run the risk of getting CEL's unless you use a defouler or have some kind of tuning to disable the second 02 sensor.

I have a new Evo and have no intention of going catless. I will probably upgrade to a higher flowing cat. You might consider doing that too.

lancer0220

iTrader: (6)

also the catalytic converter on the lancer is already a high flow, going to an aftermarket high flow will just increase noise and might actually reduce power.

LiX

iTrader: (1)

Why you think stock cat is high flow? What's it CEL rating? I think it's at least 400 CEL. High flow cats are usually 200 CEL.

M@verik

Ive done it. Nothing wrong with it.

EvansEvoSOUL

Wow did you really just say that do research kid louder means power becuz the louder means you have more air flow and more air flow is more power the stock cat is a hp killer

M@verik

Not necessarily :/ Loudness has nothing to do with power.

mshilto89

iTrader: (2)

Correct me if I'm wrong here but I am pretty sure loudness has nothing to do with power. As a matter of fact if you're driving a NA GTS (or any NA enngine in general) and you cut the cat out or do other mods to the exhaust the run the risk of messing with the back pressure and if you have low back pressure it is bad on a NA engine right? I have heard the only time you really want to open the exhuast up is on a turbo'd engine that way the turbo can spool up quicker due to the decreased back pressure.

I know when I had my 04 Dodge pickup that had the 5.7 Hemi in it I ran a true duel open exhaust on it, for about a week..... Went back to the shop and told him it was running like s***, idle was bad, seems to stall out in lower rpm (2000<), throwing codes and so on. The guy told me this was becuase I basically took all the back pressure off and it was causing the motor to run abnormally. I was like REALLY!! YOU COULD HAVE TOLD ME THIS BEFORE!!! His response was "well, you wanted it loud right?" Told him I couldn't argue with that and had to pay another $250 to have them go in and install a set of magnaflows.

Moral is if loudness has anything to do with power than my truck should have had about 700+ hp LMFAO!!!

blakroyal

iTrader: (11)

replacing cat with test pipe just makes it louder..it will be faster at take off but lose a little bit on top end..i have full trust 3 inch piping and its loud.. if you want to keep the noise down just keep the cat ..it will keep the noise down just a lil bit and safe the planet from emissions but for me i like the test pipe keep the evo happy lol

Defcon5Es

iTrader: (5)

this made me laugh for a little bit

Vivid Racing

iTrader: (98)

A test pipe (aka removing the cat) will do very little for power, but will give your exhaust a more aggressive sound. Test pipes are great on turbo cars or cars with tons of mods.

Unless you're doing a crazy all-motor build, or going turbo, a test pipe won't get you much power. Maybe 3-5HP. If you're just looking for the sound, then go for it. The loss of backpressure from just removing the cat will be minimal. You'll need an O2 sensor extension/defouler to avoid any CELs.

lancer0220

iTrader: (6)

Newbie, Please dont come onto this forum and act like you know everything.

You realize how much of a fool you look like when you say "louder means more power.." this is probably the stupidest comment ever made on evom .

Anyway yes it has been mentioned before that the stock cat on the lancer is a "higher" flow cat, what I meant by saying it was a high flow cat was just that.

For 99.9% of 2008-2011 lancers the stock catalytic converter is more than enough, only those with full engine mods or turbo set ups should consider removing the catalytic converter.

I was directing my comments to the OP who is pretty much stock minus an Injen CAI and greddy axle back, removing the cat will simply make his exhaust obnoxiously loud gains would be minimal if anything. OP would benefit more by leaving the cat (would avoid need for O2 defouler) and look into having the ECU flashed either by works or RPW.

As far as bolt ons go for the 4b12 it benefits the most from a custom ecu tune.

unkSauce

Don't forget to mention pulley! and i mean the "good" pulley!

As to the OP: if you wanna play with your exhaust look into headers. Although from what i have read it doesn't produce more power just transfers it from low to high end.

lancer0220

iTrader: (6)

the pulley from RPW/Alutec is good from what I hear, but as far as cost/performance , tune is the way to go!

Especially if you know someone with a tactrix cable (or own one yourself like i do)