Rocky,
well it really depends.. The cost of the Supra?!?! i have no idea. Garages in Sharjah! - plenty, but quality .... is doubtful. Im sure there are some good ones, i just dont knw any
.
Then again, If i do it, i probably want to get it done professionaly and with some kind of guarantee that it will get passed from the Police.
Exhaust -- well it depends - what kind of exhaust? cat-back? from the manifold? free flow? ......another question is do you want it legal? What Brand?
Cost can be anywhere from 2000 (half pipe till the tip) to about 8000 AED. (whole exhaust from manifold, wider pipe, and from an expensive store!) ....prices i have checked for my Civic SiR.
For Air Intakes, again, depends on the make. Performance Garage can prolly get an AEM Cold Air Intake between 1500 - 4000 AED.
Want something cheaper, check out Auto Plus that can get you a Simota Air Intake for 500 - 900 AED.
Engine mods, such as light weight pulleys, headers, etc. again are variable in costs. The best is for you to actually call them up or email them and get proper qoutes.
I dont think im very helpful... sorry bout that ... but it depends on the car, the make of the mods, and where you get it done! I knw people that have spent up to 20,000 AED for the mods mentioned above.
Another guy with a similar car, paid under 10,000AED.
Its always better to save up and get the best for your car. My opinion!
Cheers