Not sure if the `05 Impala 3.8 even has a resonator (or resonators) to begin with, so crawl underneath and check, or check your shop manual to be sure. If so, I would not advise removing it (or them) on this car. Any horsepower gain, if any, that you might realize from doing this would be minimal at best, and you would almost certainly create a situation where you would not be able to pass your Texas state emisions testing with this type of modification. (Although, I don't know how tight those standards are in the Houston area).
Unfortunately, most modern computer controled GM engines are disigned to work with all of their factory comopnents in place and are generally just not that receptive to these types of modifications without having some kind of negative impact on other systems within the drivetrain unless certain computer parameters are altered as well. In this case, I think this would reak havoc with the O2 and/or TPS/MAP sensors due to the change in exhaust back pressure. This might be especially true with a supercharged engine such as yours.
I'm not suggesting that there aren't ways to properly make these modifications - just be aware of the other factors that you will probably encounter in doing this for what will likely be a very minimal (or no) gain in performance.
If you are serious about increasing horsepower with this engine, there are many aftermarket parts out there for the GM 3.8 (i.e. Cams, fuel delivery and intake systems, performance computer chips, etc..), but you need to decide how much money you want to spend on doing this. Horesepower ain't cheap!