Should l get a supercharger or twin turbos? Should l leave my 3:73 gears in or should l get 4:10's. Should l down size from my 18 inch Shelby Cobra rims to some 16'' bullit rims.

definetly get the supercharger, leave the 3:73 is in and keep the 18's, the tires do not really matter but you want to have them wider in the back like 11 inches and about 9 in the front

l would go with a twin turbo, hellion & hp performance both make good kits. The turbo will be more efficient, no parasitic loss, can turn boost up/down by a knob, does not ''take power to make power like a supercharger makes more power & gets a little better gas mileage then the supercharger since the turbo allows u to stay out of boost where the supercharger builds boost once u put ur foot on the gas a little. Keep the 3.73 as if u went any higher with either super or turbo charger 1st & 2nd would absolutely be useless.

Wheel wise ur fine, all tho l would put a little bit wider & sticker tire in the back if/when u go super or turbocharged.

'' an 8 psi turbo kit will produce more peak power due to the fact that a supercharger is using a fairly large amount of power just to get it spinning. What is more important for a street car is ''power under the curve'' meaning the average horsepower produced. This is where the turbo really shines since u can have full boost at as little as 2500 rpm! This will make the turbo car feel like it has 50% more cubic inches (or more). The difference in torque at low rpm is can be as much as 100 lb ft in favor of the turbo due to the additional available boost''

1st get perform a P l head intake swap, then determine what kind of forced induction you want. l have a Kenne Bell blower on my GT and It like it alot, nice wide usable powerband. Keep the 18 inch wheels and 3.73's. With a blower or turbo setup you do not want to go too high in the gearing.

For a basic v-8 installation a supercharger is always best.

Above all do NOT LISTEN TO ANSWERER ''mike'' its very clear he has not done either a supercharger or a turbo installation. In low boost - big block installations all the efficiencies of a turbine system tend to get washed away.

Generally for low boost, larger block installations a supercharger is always more effective because
-they weigh less (no piping)
-the installation is easier & cheaper
-they run cooler & require less engine management

Turbos r great for high boost applications, extreme power,or where engine compartment space is tight or where small bore/high rev engines r involved.

Not sure whether u r asking street or strip application, but generally ur gears r ok, wheel size is ok.

If u have not done it it - u definitely require intake (plus throttle body), headers, & a decent exhaust, catbacks, & of course post installation u will need a pro-tune.

If ur engine is tight l agree with ''answerer fodaddy1'' as always best selection for a mild to mid boost supercharger will be a twin screw, either kenne bell or Whipple. Very early to engage, linear power band & really easy to increase boost (just downsize the pulley) if u decide to build out ur heads or bootm end.

regards engineer (owner present & past of modified/supercharged cars , fan of forced induction)