The drop in K&N filter helps some, but nobody is currently making performance parts for the Trailblazer. There is huge potential with a free flowing exhaust, but you'll have to design your own. I did a write up here on an experimental exhaust. If you read through it you might get some ideas. The rear muffler is the main problem, very restrictive.
No company in there right mind is going to pour resources into this platform in this economy especially. I understand people's desire for more power and performance but let's be real you bought a 1.2 T or 1.3T 3 cylinder CUV I'm really not trying to be rude but maybe you bought the wrong vehicle? There's simply not much that can be done with this platform Performance wise that will not be a one off custom design that would likely require replacing the engine or half the engine components.