It seems that everytime it rains, i have this musty smell that i cant get rid off.. since the stupid car doesnt have a air filter, whats the best way to fix this and best way to search for the leak?

 

Clean your car? How do you know there is a leak? When I bought my car from this kid it had been sitting a while so it smelled musty as all get out after the first rain until I actually cleaned it. Keep a spray bottle of Febreeze in the trunk.

 

^ +1. I would clean the car, especially the upholstery from top to bottom. Then check for leaks the next time it rains. Also, check behind your door panels inside the door and make sure the drains are clear, sometimes they can get blocked by debris.