is there an advantage to removing the emmissions stuff?

air pump? egr? smog? etc...

 

less engine bay clutter and a little weight

some will say that the EGR tube in the intake costs a few hp...but maybe 1hp at best

 

thats what i thought. but some have told me that it will make an engine run better. but i have no comparison.

if you took all that stuff off, wouldnt you throw a few codes?

 

yes...you'll throw an EGR code and an AIR code. there may even be 2 codes for each of those..not sure.

but they don't affect the running condition of the engine at all.

they are along the same lines as the rear O2 sensors, for information only.

 

There are more than 2 for the AIR. IIRC 5 or 8 related to AIR alone.

 

There are quite a few codes that need to be tuned out ($100~125). Performance wise, no real gains other than about 10lbs weight savings and a less cluttered engine bay (as mentioned above). The only real reason you should get rid of it is if you don't have cats anymore. If you still have cats, you need to at least keep the AIR.