So im trying to figure out what exactly i would need to get done to my boyfriends holden commy exer to make it sound louder..

As its his 21st coming up and his mates have stated that hes thinking getting his car done up to sound louder thought id do it for him... Only problem is dont know what it is i would have to buy or whatever.

Felt too embarrased to ask his mates so thought id try the net and get some advice.

Hope someone knows what im talking about

Thanks guys

If you're talking about making the engine sound louder, then you need an aftermarket performance exhaust system. You will probably need to ask for some help finding the right one since you need different exhaust systems for different model years and engines.