I am assuming this is a breather filter, i do not have one on my 02 Trans Am. I do have an after market exhaust on the car, stage 3 cam, long-tube headers with ram air. Is it absolutely necessary in my case? No big deal if it isn't but if it is…. This is not my engine of course, dont have the indicated filter.

 

That small filter is for the AIR system, it's needed for certain aftermarket air lids on the 2000-02 cars when the AIR system is still intact. If your car has LT headers then it's likely that the AIR system was already deleted, hence you don't have that filter (either that, or you have an air lid that comes with a provision for the AIR tube already built in, such as the SLP lid).