what does an air pump on the 2nd gerneration do? Can I drive with out it?

 

It feeds air through the engine, and to the catylitic converter. If you take it off it will clog your cats. So leave it on, or get a race pipe.

 

i also heard on serie 5, it help on opening up the 6th port, can anyone confirm whether it's true?

 

Im pretty sure that is true also...

 

With the race pipe, I take it you won't clog up a pre-silencer if equiped.

 

Nope, nothin to worry about except the cat...

 

The airpump feeds fresh air to the cat via the ACV at lower rpms to dilute the concentration of hydrocarbons particularly during the warm-up cycle when the engine is in the fuel rich mode. Removing the airpump will reduce the efficiency of the cat with respect to emissions but should not lead to clogging or anything like that. I know plenty of people who have done just that without any adverse effects.