Ok so i woke up sunday morning to go to work, i let my car warm up for about 10-15 mins then i get on highway which was completely empty at 9:00am so i got tempted to gun it , so i floored the car and when i let off after second gear i heard a loud rattling noise like if a piece of metal was loose inside the engine or tranny, what can this be? it only makes that noise after i release the load of the engine.

 

any ideas?

 

you should jack the car up and crawl under and see if anything is loose. That is what the mechanics would do and charge you an arm an a leg. Shake, wiggle and tap anything that can make noise. There might be something loose rolling around down there.

I had a rattle that would happen everytime I excelerate that drive me crazy and I found it to be the parking brake wire hitting my driveshaft.

Good luck in finding the problem.

 

Maybe a throw out bearing ?

Then again I see you have a lightweight flywheel installed.

 

test pipes rattling?

 

Ran over a mattress?