[QUOTE=vampire8668;4320130]Assalam alaikum pakwheelers
i am a diehard fan of motor cars esp. performance cars so i need some information regarding performance of a car.
as far i know (i might be wrong) that the engine performance is increased by installing/upgrading the following parts
1. cold air intake (depends upon the car) in modern efi cars the change in performance is insignificant unless u also spend money on a piggyback, and some cars come with caa configuration factory fitted
although i have installed one in my khyber carby because its airfilter box(pan) had lost its shape. but when i tune it to squeeze performance from it, i get the fuel economy worse than mark x. 
- headers
same as above, instead of spending money on hardware, you should get better software(ecu) first.
- pressure plate/clutch plate
better clutch can handle more power and eliminates clutch slipping under high torque.
- BOV
it is installed with turbo to avoid engine and turbo system damage and to prevent compressor surge.
- downpiping
it allows the exhaust gases to escape faster, but most custom downpiping setups in pakistan are done by those who dont understand it, which only results in totally opposite effect but louder exhaust.
- spark plugs+wires
better plug wire ensure a better spark but modern engines dont need them as they have coil on plug type ignition system. and best performance can be acheived by copper spark plugs, but they are less durable than their iradium and platinum counterparts.
- coilover's (for stability)
coilovers make the ride stiff(better for paved roads), improve handling characteristics.
are above mentioned upgrades are enough for better performance?? anything upgrade is never enough, it only depends upon which category you want to roll into, you can always swap a better engine, mod that too, upgrade to a better car.
how much it effects the mileage of a car?
it depends, all the upgrades mentioned above other than coilovers and plug wire, plugs increase fuel consumption.
