So much fail in this thread.
Really, just leave it alone.
Contrary to "popular" opinion, late model emissions controls do nothing bad for you and everything good. As long as they are maintained that is, just like everything else in a vehicle.
For example: EGR is evil right?
Wrong.
Recirculating egr reduces combustion temperatures. Outside of the emissions benefits, the reduced temperatures stave off knock. This allows the engine to dial in more ignition advance. Which equals more power. Far more than what the internet "experts" will try to tell you it displaces in combustible fuel/air mixture.
Air pump does nothing but help fully combust waste petrochemicals in the exhaust. It costs you one or two HP at worst. Actually, I don't even remember there being on an a 99 GMT400. Could be though.
Your exhaust system as you describe it is normal for the year. Right down to the upstream/downstream O2 sensors.
Vapor recovery systems have nothing to do with "fiery deaths" either. That's what the rollover valve in the tank is for. Vapor recovery does exactly what the name suggests: it recycles fuel "flash off" from the tank and routes it though the engine for combustion purposes. The carbon canister is what is in earlier vehicles, it's just tubing in later models.
If you start ripping things off in a misguided attempt to "de-emissions" it, you're more likely to end up with a poor running truck than anything else.
This emissions equipment is evil" thing is now an urban myth. Once upon a time, emissions were a pita, but that was back in the late 70's early 80's. Modern emissions are fully integrated into the vehicle now and are actually a plus, not a minus. That's why you have an ECM running the fuel injection in your vehicle, it's there for emissions.
Putting a couple bucks into a hi performance cat back exhaust will net you far more than any "DE-emmissioning" it ever will...
look out ram California is coming for ya 
Done and done. Shotgun shells and a spare clip in the glovebox, shotgun under rear seat, Springfield .40 on my hip. Concealed carry is legal in AZ, without a permit - I feel bad for the a**hole who ever crosses me or my family with ill intentions.
