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Discussion Starter · #1 ·
the other day i pulled my exhaust off my SRT-4 and completly hollowed out my cat converter. i could not believe the ammount of shit that came out of it !!! yea, yea, i know "why didnt you just buy the race downpipe..." well i'm really poor and also for thoes of us living in emmissions restricted states/areas and dont know somone who can "slip it through" have to keep the cat on the car. fellow PA SRT-4 owners know what i mean with the recent changes in the state inspection laws. anyways i just wanted to report that i have been driving it for a week now and NO MIL LIGHT. thats right folks the "check engine light" has not and i repeat NOT come on. as for the improvement its obvious, the throttle responce is alot better and the exhaust sounds deeper. if you decide to do this make sure you remove the O2 sensor from the converter before you start smashing.....and out it back in when you are done.
 

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Hey Cmax,

How much than louder than stock is the car after punching out the honeycomb material?

Currently I've got a MaxxFab O2, mated to a catless B&B turboback; and it's louder than hell. And it's not a good loud either, sounds like a diesel truck and is real raspy when getting on/letting off at certain RPMs. It's not the loudness that concerns me. I also noticed a drop in low end torque, it's much harder to spin the tires in first (I used to chirp all the time if I wasn't paying attention). I could just get a stainless Magnaflow glasspack resonator welded into the midpipe, but then I'd have almost 1K$ invested into this exhaust setup.

Sorry to ramble and sort of go off topic, but I'm trying to decide if I should stick with my B&B and invest more money into it, or cut my losses and sell it and go back to stock.

Right now I'm Stage 1. I'm aware that a larger diameter exhaust is more beneficial for big power... aka Stage 3 or big turbo; but I doubt I'll ever go past Stage 2 unless I win the lotto. The way it is now my car never gets to stretch it's legs, my daily commute is pretty tame; not much chance to use the horsepower.

Just my uneducated guess that the stock exhaust minus the dense catalytic material sould free up about the same power (or more) as the stock downpipe/cat mated to a borla catback. Even with the loop-de-loop bends before the stock tips.

Thoughts anyone?
 

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Discussion Starter · #6 ·
i'm running full factory exhaust, after i hollowed out the CAT i was supprised at how little the tone changed, at idle its nearly the same as before. i still have the 2 resonators on and that is where the real sound killing happens. the advantage is obvious, any an all turbos want NO backpressure so anything you do to reduce it is better for power but its no supprise that the touque curve may change...

"I also noticed a drop in low end torque, it's much harder to spin the tires in first (I used to chirp all the time if I wasn't paying attention). "

the exhaust sounds louder as it revs up, its a bit deeper but the "pops and burbles" have a sharper "crackle" sound. its not all that different. i plan on cutting out 1 resonator and see how it sounds. if i'm not happy with that i plan on building my oun cat back with 1 glasspack and thats it. i had a glasspack on my Gen 1 neon and it sounded GREAT, nice deep low tone. that car had a race headder and no cat, a straight 3" all the way with just a glasspack.

i can only assume that what i have done is very similar to using the race downpipe but i have no hard numbers to back that up, dyno runs will be in the near future. however the even smooth flow of the exhaust is interupted by the simple fact that the gasses go into the old cat chamber, a very large area and "stall" or slow down, as the psi in the cat chamber build all the air is trying to escape out the smaller opening at the back of the cat. in an ideal exhaust situation you want a good, smooth, even exhaust gass flow all the way out. so its not perfect by any means. it is however a good solution for a free-flow exhaust for people like me who need to keep the Cat on the car so i can get it inspected. oh by the way, i doubt the system would pass a real emmissions test with an ESP machine. my county only requires a "visual" emmissions equipment test to confirm the parts are in place....
 

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Someone correct me if im wrong.

1) more mid to high range power

2) sounds stock AKA not super annoying

3) less low-end torque which equals less traction problems for launching

Only question left is, is our cat a bolt on or do i have to cut and re-weld. yes i could go crawl under my car and look, but im lazy. i know what i might be doing tomorrow!!
 

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anyways i just wanted to report that i have been driving it for a week now and NO MIL LIGHT. thats right folks the "check engine light" has not and i repeat NOT come on.
Give it time. It will show up sooner or later.

-Mobotix
 

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stage 1 shouldnt throw a code for no cat...
 

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DirtySanchez said:
...
Just my uneducated guess that the stock exhaust minus the dense catalytic material sould free up about the same power (or more) as the stock downpipe/cat mated to a borla catback. Even with the loop-de-loop bends before the stock tips.

Thoughts anyone?
just fyi for all that don't know this but the stock piping has a 1.75" bottleneck at the joint on the rear axle not to mention the gazillon bends on the split... that said, i think the mopar catback with stock dp/cat will still flow more..
 

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Use a spark plug non-fouler. Bore it out and screw in the o2 sensor. Then screw the entire assembly into the catalytic converter. That's what I did when I got my needswings dp with no cat. Never threw a code, works wonderfully. Do this only if you get a code, if not....Your Golden!
 

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CMax26 said:
the other day i pulled my exhaust off my SRT-4 and completly hollowed out my cat converter. i could not believe the ammount of shit that came out of it !!! yea, yea, i know "why didnt you just buy the race downpipe..." well i'm really poor and also for thoes of us living in emmissions restricted states/areas and dont know somone who can "slip it through" have to keep the cat on the car. fellow PA SRT-4 owners know what i mean with the recent changes in the state inspection laws. anyways i just wanted to report that i have been driving it for a week now and NO MIL LIGHT. thats right folks the "check engine light" has not and i repeat NOT come on. as for the improvement its obvious, the throttle responce is alot better and the exhaust sounds deeper. if you decide to do this make sure you remove the O2 sensor from the converter before you start smashing.....and out it back in when you are done.

i'm from pa, and the laws have changed. you dont need a cat anymore...the emissions test now is a obd test. if you have no codes, you pass...supplying a dyno to every inspection shop was too expensive for the state to cover...imagine that...one more blunder of an idea by ed rendel aka jerkoff of the century.
 

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:clap: :hi: :thumbsup: :wah?!: I did the welfare exhaust and the cat punch and let me say the car is crazyloud and it sounds like a diesel truck at idel. I love the looks I get when I get on it or shut the trottle.
 
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