gut main cat - howto? - CEG Archives

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I did a search for 'gut cat' and nothing came up.

Is this an easy process? the dealer told me it was clogged, and it smells like it is. so if its easy enough i'd like to gut it.

I should notice some performance improvement since i'm taking the clogged ceramics out?

sorry, I searched under 'mystery mod' and found some good posts. I can't delete this topic myself though..

Do not let PETA catch you gutting cats...

Just buy a high flow cat from magnaflow. It's an inexpensive upgrade.

Buy a high performance type, or replace with a straight pipe. Gutting the main cat slows down the exhaust path by creating a big open chamber and it will lose power.

Rick

Originally posted by Dan Nixon:
Do not let PETA catch you gutting cats...

Originally posted by Buckshot77:
Buy a high performance type, or replace with a straight pipe. Gutting the main cat slows down the exhaust path by creating a big open chamber and it will lose power.

Rick

It should thoeretically lose you power - but with my main cat gutted and not much else (UDP, stock SE exhaust minus resonator, SVT TB and KKM) my SE got 154 hp and 156 tq. If the cat gut lost me power I must've had a heck of a factory freak to start with

Read the post...he said he searched for mystery mod, i think he means precats.

yeah, sorry i put main cat in the subject. but i'm going to gut my precats and replace the main cat w/ a hi-flow... any ideas where i can get the cheapest hi-flow cat?

YEs, you will lose HP if you increase the inner diameter of the pre-cat(s) but only in the lows. Your power loss is from the SVT TB since it doesn't compliment the UIM or LIM pathways along with the fact that the PCM cannot adjust to this without a custom programmed chip!

Originally posted by stepmar2:
Your power loss is from the SVT TB since it doesn't compliment the UIM or LIM pathways along with the fact that the PCM cannot adjust to this without a custom programmed chip!

What power loss? I was getting 10-12 more hp and tq than a stock car from very minimal mods - even the low rpm tq was higher than stock. My point was that everyone says gutting the main cat will cost power - but my dyno says otherwise. It will obvioulsy be less of a gain than a straight pipe - but it appears that with pre cats in place the restriction of the main cat saps more power than the poor flow of a hollow gutted cat shell. I will say that with a tripple gut I got huge low to mid range bog - 3 expansion chambers and cold sluggish exhaust took there toll.

Anyway, to make this relevant to his question about precats - Id offer my butt dyno based opinion formed after putting a new main cat bacck on with gutted pre cats that the main cat gut is a better mod than doing the precats - but I have no dyno data to prove that.

BTW - the SVT TB casued no problems with the PCM tuning. Lot's of OBD trace data with SVT TB on stock upper and with my dual honed 99 SVT upper and it pulls the mixture in no problem at all.

does the magnaflow high flow cat flow better than the cat in the shoshop y-pipe?? i have heard bad things about the shoshop y-pipe but i was in a pinch and had to get it at the time as i didnt know of many CSVT parts providers then. does the magnaflow actually pass smog? i will be bringing the car back to cali in a few years and cali is a b*t&h when it comes to smogtests!