everyone is going to tell you to put headers in. since you said money isn't an issue my personal advice is buy good headers, not cheap ones. everyone will tell you that you won't need any throttle mods and a custom tune is always better than a pretuned pcm.
for a 3.4 pulley all i've ever read that you actually need for sure is at least a downpipe exhaust mod and an open cone intake that i can remember. but a colder tstat, colder plugs, and a tune are usually lumped in depending on who responds and which combo. depending on who you talk to some will say you are wasting money or steps.
3.4 setup is easy to manage for the car from what i understand. i'm getting ready to put in my pulley and i'll be done. so we'll see.
if you go smaller and want to build it up i think you should build or buy a built transmission first before you go smaller than 3.4 size. a smaller pulley is really the only way you are going to get larger horsepower gains (and speed). most the other mods are just to support the different pulley sizes. and stock transmissions are not that great for these cars.
