Yes, you can put a tube on the stinger, I actually use a dubro exhaust deflector on all my trucks, my Savage SS even seems to run just a tad better with it on. The plastic piece on top of the 2.5 head is just basically a head protector, it will not affect the performance in any way if you remove it. Nor will it hurt the engine at all, other than you run the risk of scratching the head when you roll over.