Getting a rattling noise when pressing gas. Any one what may the problem.

Please check the exhaust manifold or exhaust pipe (silencers) metal covers, the bolts holding them may be loose. Check too the exhaust pipe hanger bolted to the underbody, they may be loose.

The covers if they are deformed and dented and close to the engine block at about 2-3mm apart can generate a rattling noise. Bolt mounting the exhaust pipe hanger can make noise too when loose when revving up the engine.