I finally got a hold of a new 987s (new to me). all i did was put an exhaust on there plus desnork and new springs. Then i had a engine code:
po431 - BANK 2 warm up efficiency below threshold. guessing i messed up the 02 sensor. i remember hitting it.
po456 - tank system - fine leak. no idea what that is.

can i get some help/references. thank you

 

For your P0456. I'd start by unscrewing your gas cap and just spin it to make sure it's on tight. This thread would be helpful too.

https://www.6speedonline.com/forums/...ode-p0456.html

 

Could be the sensor. They are generally tough but a blow might have damaged the thing.

A DIY test is to swap the #2 sensors from bank to bank. If the error code follows the suspected sensor well, it probably is the sensor.

If the code stays put then it can be the converter. Did you bang the converters around? They are tough like the sensors but can be damaged by rough handling (or impact from road debris). What can happen is the converter brick can become loose and exhaust gas flow through the converter is not as good as it needs to be. The loose brick can knock when cold and buzz when hot. So if you are hearing noises...

Last but not least just a plain old exhaust leak can trigger this error.

Double-check the exhaust install.