im looking to buy a 2005 mustang gt and when i accelerated during the test drive it makes a really loud noise in the cabin. it has an airaid cold air intake could that be the problem.

 

If you floored the car, the cold air would have made a difference. Otherwise, it's all part of the exhaust, whether its the drone at low rpms or an aftermarket exhaust. If its not either of those, then the factory exhaust is leaking somewhere.

 

the exhaust is stock, how would i be able to tell if there is a leak

 

You should be able to jack the car up and look around. Most likely, if the previous owner hasn't gotten the underside roughed up, it's just a loose bolt causing some opening between some joints. Though GTs are generally louder than other stock cars.

 

it doesnt seem to have a leak it sounds fine while idling and the underside is in good condition. i test drove another one and it was much quieter so im thinking i just need to replace the airbox