In my opinion (and experience)... get a good exhaust manifold like Powerzone, remove the cat. converter (you can keep your midpipe and muffler), change the airfilter and you're good to go. You may consider lightenned crank pulleys (but there may be side effects from losing the dampener - even mythology's is only half dampened), or if you can find, a lightenned flywheel (this one guaranteed improved pickup).
Other than these the rest are, IMO, very marginal gains for the money you spend. Only do those after the above... until you are prepared to spend big for big mods.