catback system is the whole piping from header till the exhaust...branded one like greeddy or hks i guess costs abt 30k here in khi...so if u have enough budget then first add intake,plugs ,plug wiring,headers and a exhaust ...then if u have money left abt 30k then best option is to do a local 2.5inch piping cost abt 1500rs and with those 30k get a nitrous.....then i guess ure can surely get head to head with B16'sssssssssssssss..