It's very hard to mod the 3.0 to 200 horses without going with either Nitrous or a Supercharger or Turbocharger (no one has done the turbo yet)...
Thats the cheapest way to get to 200 hp.
You can get your 3.0 up to around 160-170 pretty easily however. Here's how:
Cat-Back exhaust = 5-8 hp
Cone Filter (preferably pulling in cold air) = 2-5 hp
Ported and Polished Intake Manifolds = 5-10 hp
Phenolic Spacer for your intake manifold = Cooler intake + 2-4 HP
Advance Timing = 1-3 hp
Those right there should net you a minimum of at least 160hp, and up to 175 hp if your car is tuned properly and running strong!
Now, take the 160-175 and add some nitrous (50-75 shot), or a supercharger and you'll be over 200 hp in no time.
Good luck, any questions just ask. These are just a few of the known mods for the 3.0L.
well as far as upgrades i would recommend doing the port and polishing of the upper and lower intake manifold, also port and polish the heads, both on the intake and exhaust ports, also get the ingnition upgrade, those seemed to make the greatest difference in my 3.0 oh get a straigth through muffler i noticed some improvement on the acceleration at freeway speeds just with that.