Exhaust prob

[JD1980]

I recently down grade to a smaller stock pipe on 03 Baja.
My check engine light came on when was about to get inspected.
Couldn't get inspected.
Had to get new o2 sensors and bought them
Waited 1.5 week to come in
Installed and 78 mile drive to reset ECU
ECU reset and got 030 and 037 codes
Heater circuits in O2 sensor
1.5 weeks send back
1.5 weeks to get new ones
During install wires stripped out the little clip and needed a new clip.
A week to get clips
Another 78 mile drive to reset ECU
ECU reset evap won't come online and when did said evap leak Baja got smoked and no leak
ABS light came on
Still 420 and evap and now ABS
Anyone know problem, because I got a ticket already 2 months past inspection and emissions check and stickering.and was parked at mechanic because no room to put Baja in mechanics garage.

[Guacamole]

I recently down grade to a smaller stock pipe on 03 Baja.

I think I found your problem.

[JD1980]

Had a wider pipes from headers all the way back
But went back to stock size pipes from headers back

[JD1980]

Stuck a ODB2 on it
First was 420
Got the whole exhaust in from headers back,
Old exhaust went from stock off headers to 3" y pipe up to 3.5" resonator pipe to 5" resonator down 4" pipe to 6" can muffler with 5" tail and quiet can,
New exhaust is stock size
Then all mechanic said was evap leak and smoked it but no leak,
at first was thinking fuel injectors so dumped a bottle of Lucas engine treatment with a full tank of E94
Then with 030 and 037 so replaced the O2 thinking was heater circuit
Just checked it myself and got P0134
And was telling them check the maf sensor which can be prob but they kept saying the O2 sensor.

ABS prob can be purge valve or some wiring connection or even when got my rotors hubs and bearings replaced the little thing with the lines wasn't replaced so the abs wiring can read it.

[Guacamole]

Stuck a ODB2 on it
First was 420
Got the whole exhaust in from headers back,
Old exhaust went from stock off headers to 3" y pipe up to 3.5" resonator pipe to 5" resonator down 4" pipe to 6" can muffler with 5" tail and quiet can,
New exhaust is stock size
Then all mechanic said was evap leak and smoked it but no leak,
at first was thinking fuel injectors so dumped a bottle of Lucas engine treatment with a full tank of E94
Then with 030 and 037 so replaced the O2 thinking was heater circuit
Just checked it myself and got P0134
And was telling them check the maf sensor which can be prob but they kept saying the O2 sensor.

ABS prob can be purge valve or some wiring connection or even when got my rotors hubs and bearings replaced the little thing with the lines wasn't replaced so the abs wiring can read it.

So, you replaced the entire exhaust and your O2 sensors are throwing codes left and right. I don't intend this to come off as mean but you do realize they were programmed and built specifically for a stock Subaru-designed exhaust system, or a close approximation yes? If you deviate from stock, especially with the catalytic converter and header pipes, you're going to encounter serious problems with the O2 sensors. Even something small as changing the diameter of the header pipe changes the pressure and volume levels, and the O2 sensors are going to detect this change and start throwing codes thinking something is seriously wrong with the engine. Your cat-back doesn't matter as much since there's no sensors, but doing something drastic like going from a 2in diameter cat pipe to a 1in diameter midpipe will choke the system and cause problems.
Not to mention if you removed the cats from the exhaust that's moronic for two reasons:
1. it messes with the O2 sensors as previously mentioned
2. it's a federal crime in the United States.

[JD1980]

New exhaust is stock
Everything is tuned to old exhaust like stage 5 tuning and direct aspiration to charger then to air filter then to intake manifold so intake air went straight to the engine and side air from wheels used on cabin.
Charger is gone and everything is already back to stock.
With new stock size exhaust got 030, 037, which was low reading and also heater circuit and now 0134.
Which with replacing both O2 sensors on new stock size exhaust with stock size o2 sensors get the 134 my first thought was MAF(mass air flow) sensor since no maf is on the 2003 am thinking could be MAP(mass air pressure) or a crack in plastic intake which I noticed around the wheel well intake but duct taped it to seal it off.
I never mentioned not using cats the cats were there between y pipe and resonator pipe they stayed stock, but I even replaced cats with stock size and whole exhaust from headers back with stock size when got 420 code, it's just some connection is wrong with bank 1 sensor 1 and when it gets fixed can then get the emission sticker.
I already passed inspection but never paid sticker because it was 60 to get inspection and 60 to get emission but 90 if got both together, and was waiting to get both together.