i just bought a 1989 lx 5.0 5 speed, it has a custom made offroad h pipe, and has no o2 sensors on it, and the cars runs great, and sounds good, and idles fine.
is there some trick people do to elimnate them, and how is the car running without them?
They're not necessary - but they are desirable in my opinion on a street car. Every time you start the car cold it can't use it's O2's until they heat up enough to provide a signal. Everytime you accelerate at w.o.t. the ecu ignores the O2's sensors -- it's called open loop, and when the ecu operates that way it ignores the O2's. Without them, it simply operates in open loop all the time. If you had them, it could go into closed loop, and this would allow you to get marginally better gas mileage.
The guy who converted mine 'lost' an important plug from the wiring harness when it got hung up pulling the harness throught an opening behind the strut towers. As a result, there was nothing to plug the O2 sensors into. The car ran for 6 years and 25K miles that way with no problems at all. In fact, I didn't know anything was wrong until I pulled the motor/harness and found the problem.
So -- have the bungs welded in, add your O2's and get them hooked up - your car will get better gas mileage. But you don't absolutely have to have them.