After this coded show up the engine starting to sound weird ! everytime i rev up or step on the gas the engine sound very loud and tired !
The code is p1456 (manufacturer control axuiliary emission controls )
I went to this auto shop and checked he said it was the o2 sensor on my aftermarket header that caused the problem but i didnt believe him i went online and check some said about Fuel tank system ?
Any solutions or anybody know about this problem pls help ! really appreciate it !

 

Fuel pump is headed south and starving the engine for fuel or the O2 sensor is shot and giving a terrible reading to the computer which intern gives a terrible air fuel mixture.

I would start with an O2 sensor as they are fairly inexpensive, and typically easy to change.

 

I'm with 1998GsRIntegra, i think its the 02. just change it

 

I also agree with the above, maybe also pull the cat and install a test pipe.

I would also like to know what fuel pressure is when RPMs are up. 94

 

Ditto this as well. Make sure the cat is not collapsed on the inside and blocking the exhaust gasses from exiting.