My advice is get the sled running tip top before you do anything to it and also do a few preventative maintenance mods.
Put a set uni-filters on the throttle bodies to keep belt dust out of the engine (poor design). Next, replace the low pressure fuel pump from under the engine and remount the new one in the right footwell. Plus, make sure the battery is good and the ground connections are clean. Run the 07 map.
Then, do some clutch work -- Cudney, Dunn, Goodwin. All of them are good kits and make the sled rock!
Keep a good belt on, riding high in the secondary.
Crank shop pipes are certainly worth some horsepower. You will need to add a boondocker as well and do some tuning of course.
Nitrous will get you big numbers. Some have even added turbos. Big bore kits, domes, reeds, and just about any other pipe and can combo etc. are not really worth the $ IMO.
Also, check the Mach forum over on dootalk, but don't get too frightened over there when you see the carnage!