I spoke to a local dealer and i was telling him how i want the power of a catless down pipe and up pipe, but i want a legal-factor of the ones with cats...

we really cant get away with catless anymore, because cops have those long mirror-on-a-stick thingys and check thouroughly for cats, plus i heard it somewhere around a $5000 fine... its a ***** aint it? i thought the car would be impounded, but whatever...

he suggested...

take out ur up pipe and knock out the internals of the cat... he says it sounds great, and you get great flow... plus visually there is still a cat present ... knock out the internals of the cat in the down pipe as well... this shouldnt be too attractive to cops and u gain about 12-15 hp, or so he says...

How do you guys feel about this alternative? because i know a cop would haggle me over an HKS catback, but catless hi performance UPs and DPs sound like cop magnets... anyone had their share of trouble? paid consequences? went with alternatives?

also, does anyone on here drive a daily driving, reliable WRX that runs low 13s legally? sounds tough... please lemme know guys!

 

Here is the insight I have gained in my 11 years of Turbo Mods:

1. 99% of modified turbo cars will pass an emissions test with 1 high-flow cat. Though you may not pass a "visual" inspection.

2. I have a gutted up-pipe, It is a bit of a chore, but I believe it is safe and effective.

3. There are great benefits in removing 1 of the 2 cats after the turbo, or replacing both with a downpipe with 1 high-flow cat.

4. A resonator on an extremely loud exhaust system "won't" save you. The back muffler still does most of the noise reduction work.

5. Lastly, if you fear police harassment, keep your car looking and sounding as stock as possible.

This is what I've learned through experience.

 

Hey thanks folks for all the info... im just wondering about the gutted up pipe... how loud is it? and when drwrx mentioned how the last canister is doing most of the work, this means....

i want an HKS Hi-Power catback... i want full power for the strip, but i behave on the street, so a silencer is something im seriously considering...

according to you drwrx, you're saying that ill be fine for smog with an HKS Hi-Power catback... Perrin downpipe (w/ hi-flo cat)... and a gutted up pipe?

In that case, I would pass visual (looks like i got a cat on the UP, and i do have a high flow on the DP) and the whole deal right? And i wont have ANY noise problems, if i slap a silencer on the HKS, correct?

and final question.. how is performance of a gutted UP, compared to the aftermarket ones? diameter difference? performance diff?

Thanks again guys, thats a lotta great info

 

The issue with the visual inspection will vary by state, and by who does the inspection.
The law says it is illegal to remove a functioning cat. If the inspector knows your model of car well enough to know that the WRX has a cat in the down-pipe and one in the mid-pipe section than any replacement of the dp or the mid-pipe would qualify as failure. However, if your inspector doesn't know what to look for, or is not concerned with that aspect of the inspection than that issue may never arise (inspectors are not required to police the cat laws). Also, many states only require a "sniffer" or "exhaust gas" test, in which case the visual is not an issue at all. And, as stated before, the vast majority of modified turbo cars will pass an exhaust gas emissions test with one hi-flow cat. I have known of people who attach the heat shields from the stock exhaust pieces to disguise their cat-less systems.

Resonators are an entirely different matter. There are many designs to produce varied results. Some are built solely for the purpose of modifying the exhaust circulation for acoustic affects. For example, there were a number of resonators in the 70s and 80s designed to mimic the exhaust note of big bore v8s. While this created a more bassy, low growl tone, it did not lower the decibel level of the exhaust. Some are disigned to remove the exhaust "spike" that accomodates drastic throttle change. Hit the gas hard and come off, you'll hear it, and if you remove every resonator and cat you'll REALLY hear it. Some resonators are actually designed to "add" back pressure at certain points in the exhaust flow, and this is not ideal for a turbo charged vehicle. On some normally aspired vehicles this can actually improve some aspects of performance.

Is your head starting to hurt yet? As a rule, I recommend doing some research before doing exhaust modifications that fall outside the "norm".

That being said, I've not heard of many people not passing emissions due to a non-stock cat-back system.

 

hahaha, head hurting? very much thanks for asking...

Wow, well i dunno what to do, gut both up and down pipe??? yikes man, then add the HKS cat-back? Just concerned about noise levels... because if it doesnt sound too suspiscious, its ok, i can pass smog, i guess...

As far as resonators go, i wanna stay away from 'em... just wanna keep things as close to the norm as possible

to sum it up, im VERY confused as to what mods to do now

My goal is to run VERY low 13's if not high 12s, keep the reliablity level, and keep it as legal as possible besides, its illegal to touch the cats if they are in WORKING condition how would they know it didnt fail or something?

Thanks everyone

ohhhh and silver! how are you planning on passing smog?????

 

I notice you are from California, "the land of uptight emissions."
Based on that, this might be a way to go:

If you plan to stay with the stock turbo, gut the up-pipe, remove the down-pipe and mid-pipe, (butkeep them) install a catless dp and midpipe, either as a one-piece unit (hks, buschar raceing, ect.) or as seperate units (XS engineering, stromaug, ect) and use the heat shields to disguise your replacement piecs, just in case an officer decides to take a look.

When emissions inspection time rolls around replace the aftermarket units with the stock pieces. There should not be an issue with the missing heat shields. I'm not aware of any law that says they can't be removed.

Your exhaust will be louder, but there are a number of cat-back systems that are not excessively loud. The HKS Hi-power is just 96 dbs, ten more than stock. If you are worried, go as quiet as you can. Here is a link with comparisions on 13 units taken from Turbo Magazine it has hp and toque gains, as well as sound, weight and price:
http://www.mattrandolph.com/wrx/cat-...omparisons.htm

I would not recomend gutting the dp or mid-pipe, you will need them intact to pass emissions. Unless you have spares and can swap out. Besides, the replacement pieces I noted above are not that inexpensive and will give better performance than gutted stock pieces.

 

Hey Drwrx, thanks soo much for that suggestion, in fact its PERFECT... I was really wondering wtf to do, but ur suggestion makes perfect sense, to cover the pieces with the heat shields, and ten swap em out with stock when emissions time rolls by

I'm pretty convinced on gutting the up pipe save for a post i read today regarding the up pipe not being completely CLEANED and ending up blowing the motor, any ways of ensuring the up pipe is 100% clean???

About the DP, i wanna go with the Perrin Catted, one is a sound reason, also i like the build quality... and plus, it replaces 2 cats with one, and i think thats enough performance value... dont you?

CEL lights??? Will i get any CEL for the gutted uppipe? what about for the Catted Perrin unit (Since it has one)??

Anyone gotten a CEL off a gutted up pipe?

thanks people! lots of great help

 

As for the CEL on the uppipe, expect one. The factory uppipe EGT sensor is on the back side of the cat in the stock uppipe. Once the cat is out of the way, there will be a LOT more air-speed hitting it, thus causing more voltage, thus causing a CEL. I know I got one in my aftermarket uppipe, and you should EXPECT one with a gutted pipe for the same reason.

However, FEAR NOT.

Go to Radio Shack and buy a 2.2k Ohm resistor (1/4 watt). A pack of 5 is roughly $1.

Take one of them, bent it into a U-shape and then loop the ends (so it looks like a U with bulbous points on top).

Find the cable leading from the uppipe. This is the EGT Sensor cable. Follow the cable from the uppipe to where it clips (underneath the boost solenoid cover).

Unclip it.

Stick resistor into holes (complete the circuit) on the engine side (not the sensor side) of the cable. It will only go INSIDE one.

Wrap cable with copious amounts of electrical tape.

tie off sensor cable with zip tie.

You are now CEL free. I'll post some pics in a few minutes.
-Etch

 

This is what a resistor package looks like

 

The U-shape with the looped ends looks like this (it makes the connection in the cable more reliable.)

 

This is where you can find the EGT sensor cable. It comes unhooked with a little work. You can see the installed resistor-mod in the lower left corner.