also in answer to some of your questions and comments... honestly before i was getting something like 29mpg... and now probably 23ish... right along the lines of what darewood said as far as loss but my thermostats not stuck open... yea i did everything at the same time (when i replaced the sri with the cai i cleaned the MAF and the throttle body but they werent really dirty at all), for the next couple weeks it was running great with small but definately noticeable power gains.. no problems at all till i took it on the trip

 

if your thermostat opens too soon, it's almost the same as if a proper one was stuck open...open road+no fan+lots of airflow=bad fuel economy...use the scanner to read engine coolant temperature while you go for a drive in similar conditions to the trip you took, speed, type of road for like 10 minutes or so and keep an eye on the temp (don't go until you reach your highest operating temperature...if it's like 140-160 or something, that's not good...get a proper thermostat.

for the cat, if you don't have to pass emission testing, and would like to further violate nature more than you already do, you can gut the cat, but then you'll still have the code i have a highflow cat, but i got it for the turbo. gutting your cat won't increase power much...

just replace it...could be just a bad sensor too though...

 

damn.. ok... im probably gonna do the cat first... then ill drive it an watch the temp. and post the results thanks for the advice

 

My thermostat was stuck open when I first got the car thought that was causing my low mpg replaced it and nothing mpg still the same I should have mentioned this in my first post sorry!

Edit 1 I'm thinking the upper o2 sensor is reading slow cause it could be working at the bare minimum and still not throw a check engine light and effect short term fuel trim