So I've been getting a really bad rattle especially when in drive and foot on brake and turned out to be the catalytic converter heat shields that were really rusted and falling apart in chunks so I just completely removed them, can this cause any problems down the line? Thanks.

 

It's there just in case you drive over grass. It gets so hot it could theoretically start the grass on fire. Other than that you're fine

 

ah ok, thanks.