i got info that the rattle at 6000rpm might be the heat shield on the exhaust. - Sorry if i sound like a newb, which i am but where exactly is the heat shield? - and can i fix it easily at home?

 

Yes, easily. The heatshield is above the catalytic converter (the one that usually breaks). Its held up by a couple bolts, jacking the car up securely will take longer than the actual process of removing the heatshield. I hope this helped a bit. Good luck.

 

What does the heatshield protect? Do i really need it? will it void my warrent?

 

it protects the bottom of the car from the cat. but no you dont really need it, its not really big deal