the after market exists for you now. the 08/09 v-6 same, 4l, rated at 210hp(@5300rpm) torque 240 (@3500)
if you want to modify your car, i would advise you to do it through (and after discussions with) a performance service centre of a nearby ford dealer (not all ford dealerships have performance groups, so you may have to search). primary reason (besides the fact they know ford), is they will be able to advise you on what can be done/where your car can be modified without a k.o. on the warranty (if that's important to you, was not to me my 04's warranty was ko'd 18 mos after purchase).
you have a fine car & lots of performance options are available.
1)chassis, ride & set up. all mustangs look better lowered (on eibach or equivalent springs), stronger sub chassis connectors, and antisways will stiffen up overall car, improve handling.
2)get - go: hopefully you are running a standard transmission in which case you can install a short shifter, followed by improved gears in the rear - end (3.73's), not a power gain just quicker.
3)enhance your power via CAI and a performance manifold, performance underdrive pulleys and a dual exhaust system with catbacks and dial up the engine with a tuning chip.
this will likely add 25-30% hp gain plus make you very quick from the start.
these modifications are all "typical" enhancements that many (in due course all?) mustangs have done to them....because of your weight advantage this will bring very close to if not quicker than most stock gt's., and overall will handle better.
now if you are really serious, the mustang 6 is a 1st rate candidate for a supercharger or a turbo charger. installation kits are available...and shelby has recently announced a complete build/install which will a take a new stang 6 up in the territory of +350 rwhp, which means you will be able to outrun any stock gt on the street, plus most modified gt's cause you're much lighter and added benefit, you will still be a daily driver enjoying same basic gas mileage as stock v-6 cause added power only kicks in at full throttle (boost).
now the shelby pkg. is a complete kit (engine upgrade, wheels, bodykit, wheels, suspension, etc etc)....likely cost will be equivalent to cost of a bonestock mustang 6 (which isn't bad considering its a better car than most modified gt's on the road, and likely carries warranty on the install.
you can ck out the shelby website if you are interested for the dealer nearest you.
you can attain same levels of performance with other installations and if you are seriously interested you can contact me as i am assembling information, have been in contact with performance shops re possibility of a new build for next yr. enhanced mustang 6 to run streetable at 400-420 rwhp (notch above the terlingua project...you can search mustang terlingua to see). but also waiting to see if rumors
come true and mustang intros new twin turbo 6 for 2010.
cheers (04 cobra running 575rwhp)