I am in a county here in colorado that does not require emmissions. What parts of the system can I remove on my 81 that will improve performance?

 

Legally, nothing.

With that out of the way.

The exhaust system is the only portion that you can remove that will improve performance.

You have choices to either just get a catalytic converter replacement pipe.
Put on a complete racing beat exhaust system.
If you have the original stock converter, then replacing it with a high flow Bonez catalytic converter system would be beneficial.

For more options and information on exhaust upgrades or such please do a search. We have hundreds of threads on the subject.

Removing the air pump, rats nest, etc... Does nothing for performance. It just cleans up the engine bay. For alot of those who have removed the rats nest the only thing that they have accomplised is gaining vacuum leaks and driveability issues because it was not done correctly.
You can do mods on the stock carburetor if you are doing away with the emissions also. This is all covered in threads in the archives.

For further info on performance upgrades please visit the FAQ section for the performance upgrade link.

 

I was thinking more along the lines of fuel usage. If im lucky I get like 20 mpg. I dont want to remove anything I dont mind the little rat nest on top the engine at all. Im just wondering if there is anything that can be shut off in addition to the catalytic converter Im replacing the clutch and had planned on pulling that off.

While were on the subject. I am going to replace the fuel filter as well is there anything else I should look at while I got the lil bastard up on blocks?