I have a 96 trailblazer stock except that I just had it bored .020 over and the head milled .020. and removed the oil injector. I have never messed with the carb except to clean it or turn the idle or air mixture screw. It used to bog down when you would punch the throttle. My question is what size is my stock jet and should I change the jet size to compensate for the increased compression. And how could i inprove my Throttle response.

 

Yes you need to increase jet size. However I would suggest boring your carb (ritter does this for $60) It will give you some additional performance and more throttle response. However jetting still needs to be increased It's not an exact science but I would probably go 2-3 sizes larger on the main to start and tune it in from there. I would also change your pilot jet.

Back to your carb and how to change the main jet is very simple. Remove your airbox and loosen clamps so you can get your carb loose. Flip it on it's side or upside down. On the bottom there is a nut remove it and inside is your main jet.(you might want to get something to catch the fuel the comes out when you remove the nut)

To change the pilot you must remove the 4 screws on the float bowl and inside a tube you will find your pilot jet you will need a small screwdriver to remove it.

DO NOT over tighten your jets just get them snug.
also keep your hands clean from dirt and grease while working on your carb.

A thing I usually do when working on my carb is this. After I get the carb free I'll get a towel or large rag and lay it across my bike to separate the carb from the engine area. Just in case you drop something.

Good luck